Evaluate

Author test cases for your MCP server, run them across models, and gate pass/fail on deterministic checks plus optional LLM-as-judge.

A benchmark score doesn’t tell you whether your server holds up in production. Evaluate lets you pin down the behaviors you care about — which tools fire, with what arguments, what the final answer looks like — and run them across the models your users actually use.

Requirements

Evals are available to both signed-in users and guests. Guests authenticate automatically using their guest session, so no sign-in is required to run or generate tests.

How it’s organized

1. Project

   Holds your servers and your suites. Everything below lives in one project.

2. Suite

   A group of cases plus the defaults they share: attached servers, models to run against, default checks, judge config, and argument-matching mode.

3. Case

   One scenario you want to verify — a prompt (or a sequence of prompts), the tools you expect to fire, an optional expected output, and the checks that decide pass/fail.

4. Run

   One execution of a suite. Produces iterations — one per case × model. Each iteration has its own transcript, tool calls, tokens, duration, and verdict.

Authoring a case

Click New case in the suite header (or in the empty-state screen when no cases exist yet) to open the case workspace. The case is a draft until you press Save — backing out without saving leaves your suite unchanged.

Case workspace

The case editor is a two-pane workspace. The left column is where you write the case; the right column shows the selected trial — a live run in progress, a persisted iteration from history, a recording session, or a spec preview.

Left column — the case form

Every case opens in this form, however it was authored — in the app, through the CLI, or from an SDK suite file. It has four sections:

• User asks — the prompt the model receives.
• In the app — interact steps (clicks, typing) recorded against a live widget, shown in the order they run.
• Scorers — everything that grades this case, grouped by the link of the user-value chain it measures, in the same vocabulary the suite’s Grading tab uses.
• Judge · Goal completion — the goal sentence, and what the judge will actually do with it.

Scorers

One list, one Add menu. Each row says what it checks, who wrote it, and what a miss does:

• Route — the first row under Selection. It answers “which tool should handle it?” and carries that answer’s strictness: Reach the tool allows extra calls, Exact route requires the exact order with no extras. The route is always a Gate.
• Step N — a check written as a step (what the CLI and the SDK produce). It is graded in place, at its position in the run, and is labelled by that position: a step-level “no tool errors” reads No tool errors so far, because it only sees the transcript up to that point. Editing one rewrites that step; it never becomes a case-level check.
• This case — a check you added here. It is graded once, over the finished transcript.
• Suite — a default the suite applies to every case. Read-only here, with a link to the suite settings.

A row’s role says what a miss does: Gate fails the trial, Warn highlights the miss without failing it, Report only records it. The control appears when your deployment supports check policy; otherwise the role still shows, read-only.

Because a failing gate halts the run, a check written as a step can leave later checks unrun. The trial column marks those Skipped.

The route question

The answer here is what marks a case negative — never an inference from its steps:

• A named tool — the case must take that route.
• No tool should be called — a negative case. It passes only if the model called nothing. A check that requires a tool call contradicts this, and the form says so.
• Any route — the case names no route and is graded by its scorers. This is a normal positive case, and it is what most CLI- and SDK-authored cases are.

A brand-new case that asserts nothing at all must answer this question before it can be saved or run: without a check, a goal sentence, or a named tool, it would pass vacuously.

Judge · Goal completion

The card shows which model grades this case, against what threshold, how many suite criteria also apply, and whether the judge runs automatically or on request. All of that is the suite’s; Edit in suite settings goes there.

What the case owns is the goal sentence, and the hint under it says what the judge will actually grade against:

• A goal sentence — the judge grades against it, and the suite’s criteria still apply.
• No sentence, but a route — the judge grades against the expected route.
• Neither, but suite criteria — the judge grades against those.
• None of the above — the judge grades against the request itself, with its score capped at 0.85.

Skip the judge for this case turns the judge off for this case only. It applies to the next saved run.

Also in this case

A case can hold steps this form has no section for — a second prompt, or a pinned tool call. Those are listed at the bottom of the column with the turn they belong to. Click Edit in Steps to open the full step list.

Steps

Steps (top right of the column) swaps the form for the flat, ordered step list, in the same workspace with the same trial on the right. Back to form returns.

Right column — the selected trial

The trial opens on its Scorecard: the same scorers the left column lists, in the same order, each with what happened to it on this trial. A row shows its result, its provenance, its role, and — where there is one — the reason, which for a step is the message the runner recorded.

The summary line counts gates only: “2 of 2 gates passed · 1 warn”. A Warn miss is shown on its row and never counted as a failure, because it did not fail the trial. A scorer with no result reads Not measured rather than passing by default. The verdict word itself stays in the header above.

The judge’s row hosts the judge panel, so labelling a trial works where the judge sits. Under the rows, Score rows expands the raw score contract, including any row the backend could not join.

The other tabs are unchanged: Chat, Tool Calls and Trace show the transcript, and Steps shows execution order — now with the same check names the rest of the page uses and the reason under a failed step.

The right column resolves to one of these views, in precedence order:

1. Explicit history pick — a trial you selected from History.
2. Recording — a live recording session is active.
3. Live run — a quick run is in progress.
4. Latest — the most recent persisted iteration with a trace.
5. Spec preview — the authored steps rendered as a conversation preview.
6. Empty — no trial yet; start typing a prompt.

A negative case is one you marked No tool should be called. Meta questions (“what params does search take?”), conversational drift, and ambiguous prompts are the usual shape. A case that simply names no tool is not negative — it is graded by its checks.

History inspect

Click History in the trial header to open a list of past iterations. Selecting one freezes the left form on that trial’s snapshot — the exact steps, checks, and settings that were in effect when it ran — so you can compare what you see in the trace against what was authored at the time.

While a trial is frozen, an Inspecting banner appears at the top of the left column. If the current draft differs from the frozen snapshot, a Changed indicator appears. Click Edit case to return to the live draft; the selected trial stays visible on the right.

Next run sheet

Click the Model, Trials, or Host chip above the form to open the Next run sheet. It separates two kinds of settings:

• Saved with this case — Trials and Model are written to the case before every quick run and on Save. Changes here persist.
• For this run — Host applies only to the next run and is not saved to the case.

Click Suite settings in the sheet to configure hosts and other suite-level defaults.

Case attachments

Case attachments require a pinned computer environment on the suite. The attachments panel is hidden for draft cases and appears only after a case is saved.

Each saved test case has an Attachments section at the bottom of the case editor. Files you upload here are seeded into the iteration’s fresh sandbox at /home/user/attachments/<filename> before the model’s first turn runs — so the model finds the same files on every iteration, model, and re-run.

Limits: up to 20 files and 30 MB total per case.

To add files, click Add file and pick one or more files. To remove a file, click the × next to its name. Changes take effect on the next run.

When attachments are present, a note is automatically prepended to the case’s first user turn listing each file’s path, so the model knows where to find them without you having to mention it in the prompt.

Fail-honest behavior: if a file cannot be seeded — because its stored content is no longer available, the download fails, or a cap is exceeded — the iteration fails immediately rather than running silently without the file. This prevents a case that relies on a file from producing a misleading passing result.

Recording widget interactions

If your MCP server uses MCP Apps (widgets rendered in a sandboxed iframe), you can record real in-widget interactions — clicks and typing — directly into a test case as interact steps.

Click Start recording in the In the app section of the case form. The button is disabled until the prompt is non-empty — type a prompt first, then start recording. Once active, a recorder shim is injected into the widget sandbox. Every click and text input you make in the widget is captured as a locator-stable interact step and appended to the case. The locator is built from stable identifiers in priority order: data-testid → ARIA role + accessible name → visible text → CSS path. This means the recorded step resolves to the same element when the case runs headlessly.

Recorded interact steps and widget assertions appear in the In the app section in the order they were captured. This order is also the execution order — the runner processes steps sequentially and stops at the first failure.

Widget ui/message follow-ups

Some widget interactions send a ui/message back to the host (for example, a cart button that says “Show my cart”) rather than calling a tool directly. During eval execution, these follow-up messages automatically drive a continuation model turn — the same way Playground handles them live. The resulting tool call (e.g. view-cart) is attributed to the same interact step’s turn, so a Tool was called check on that turn sees the call.

This means an eval case can faithfully verify a full widget interaction sequence: prompt → widget renders → user clicks → model reacts → tool fires → assertion passes.

What the trace shows

The Chat/Trace tab renders widget tool calls as the same app-attributed cards you see in Playground, so you can inspect exactly what the widget returned and what the model did with it.

• JSON tool results — Tool outputs that are JSON (including JSON wrapped in a text block) render as structured data in the card’s Data tab rather than as a raw text block. There is no duplicate result row below the card.
• Frozen widget diagnostics — When a widget was captured as a screenshot during the run, the card’s Sandbox tab shows the recorded policy: resource URI, CSP declaration, permissions, permissive mode, and any console errors or blocked requests logged during that run. Live-only fields (sandbox attributes, lifecycle, view origin) show as not recorded because they are not available after the run completes.

The screen recording

The Replay tab plays a recording of the run beside the screenshot filmstrip, and every step that captured an offset seeks the video to it.

Unattended runs on a hosted browser are recorded at 15 fps. Idle time is held rather than dropped, so the file’s duration matches the run’s wall clock even when the page sat still for a minute — the frame count above the player is the number of distinct frames, which is small on a page that did not move and is not a sign of a fault.

Recordings stop at 60 MiB and say so. A capped take is a complete, playable beginning of the run, not a corrupt file and not the whole run: the player shows a Stopped at the size limit badge, so a twelve-minute recording of a forty-minute run is never mistaken for the run itself. Long runs that routinely cap are the signal to shorten the case rather than to distrust the video.

A run that never uses a browser tool records nothing, and costs nothing.

Checks are what actually decide pass/fail. They’re pure functions of the iteration transcript, so the verdict is the same every time you replay it — which is the property you want if you’re using Evaluate as a regression gate.

Set defaults on the suite; override per case with inherit (use suite defaults), replace (use only the case’s list), or extend (suite defaults, then the case’s list).

Check	Passes when	Scope
Tool was called with…	The named tool was called with arguments matching your spec (per the suite’s argumentMatching mode).	Turn or case
Tool was called at least once	The named tool fired at least once across the turn.	Turn or case
Tool was never called	The named tool did not fire. The core of negative cases.	Turn or case
First tool called was…	The first tool call in the turn matched the named tool.	Turn or case
Response contains…	The final assistant message contains a substring.	Turn or case
Response matches regex…	The final assistant message matches a regex.	Turn or case
No tool errors	No tool call returned an error.	Turn or case
Final message non-empty	The model produced a final assistant message.	Turn or case
Widget rendered	The named widget was rendered during the turn.	Turn or case
Widget render latency under N	The widget rendered within the specified milliseconds.	Turn or case
Widget no console errors	The widget rendered without console errors.	Turn or case
Token budget under N	Total token usage stayed below the cap.	Case only

When a check is authored on an individual prompt turn it is evaluated against that turn’s slice of the transcript — tool calls, assistant message, tool errors, and widget observations for that turn only. Token budget under N is case-only because per-turn token usage is not reliably captured; all other checks are turn-scopable.

A per-trial token ceiling is not a spend control. It is set without seeing what the suite normally uses, it is in a unit that is not comparable across models, and it goes stale on every prompt or model change. Token budget under N remains a valid check and keeps working wherever it is already authored, but for spend, two things replace it: cost on every run, which shows what a suite actually costs, and --max-cost-increase-percent, which fails CI when a change makes the suite more expensive relative to its own baseline. For a ceiling on what the whole organization may spend, see the spend budget.

Harness system tools in assertion dropdowns

When a suite is configured to run under a harness host (such as Claude Code or Codex), the tool-name pickers in the case editor also offer the harness’s native system tools — for example bash, read, webSearch, WebFetch — alongside your MCP server tools. This lets you write assertions like Tool was never called for bash or Tool was called with… for read without having to type the wire name by hand.

System tools appear only in assertion pickers. They are not available in pinned tool-call steps or widget-assertion “View (tool)” selects, because those require a tool that MCPJam can invoke directly.

If an MCP tool and a system tool share the same name, the MCP tool takes precedence and the system tool is not added to the list.

Argument matching

Tool-call argument comparison runs in one of three modes, configured at the suite:

• partial (default) — every expected key must be present and match; extra keys in the actual call are ignored. Best for “I care about query and limit, not what else the model put in.”
• exact — actual args must equal expected args, key-for-key.
• ignore — only the tool name is checked.

Type placeholders ("string", "number", "boolean") match any value of that type, which lets you assert shape without locking in a literal.

Validator settings

Each suite has default validator settings controlling how tool calls are matched. Override them at three levels:

Level	Where	Persists?
Suite default	Suite settings → Default validators	Yes
Case override	Test case editor → Validators	Yes
Run override	Suite header → validators (sliders) icon	No — one run

A run override shows an override badge; click Reset in the popover to clear it.

LLM as judge

For cases where “did the right tools fire” isn’t enough — anything graded on the quality of the final answer — the judge grades the run against your expected output if you set one, and against the user prompt otherwise. It’s advisory: it produces a score and a rationale, but doesn’t gate the run unless you ask it to.

• On by default at the suite level. The cost is gated by an explicit Run judge click on the run-detail page — it won’t run for every iteration unless you turn auto-run on.
• Calibrate per suite. Judge scores aren’t comparable across domains; a 0.7 on one suite isn’t a 0.7 on another.
• When grading against the prompt rather than an expected output, scores are capped at 0.85 — you can’t get a “perfect” without saying what perfect means.

Open a completed run and find the LLM as Judge panel (labelled Goal judge when shown inside the suite results split). Pick a judge model (default: openai/gpt-5.4-mini) and a threshold (default 0.7), then click Run judge. Each case gets a score, an advisory verdict, a one-line reason, and rubric hits. The judge never runs automatically unless you enable Auto-run in suite settings.

Judge results are also accessible outside the app. mcpjam cloud eval status returns a judges block in its JSON output with each grader’s status, summary, model used, threshold, and per-case grades. To request grading from the CLI, use mcpjam cloud eval judge --run <id> --project <name>. See the cloud eval judge reference for the full flag list, including --force to re-grade and --enable to grade a run recorded before the judge was turned on.

The same judge config and defaults are shared with Swarm journeys. When creating a new journey, expand Advanced → Judge to set the judge model and enable auto-grade for that journey. Session score badges (showing the verdict and score) appear in the Sessions list and run matrix cells whenever a session has been graded. Sessions with no transcript still expose the on-demand judge entry point so failed or empty sessions can be graded against the journey goal.

MCP App widgets in swarm sessions

When a swarm session uses MCP App tools that return widgets, the session viewer replays those widgets as full interactive components — the same rendering you see in the Playground. Widgets are captured per turn as the run executes and are available once the run completes.

During a live run, MCP App tool calls appear as plain tool pills in the session pane. The interactive widget renders once the run finishes and the snapshots are persisted.

Running

A run needs three things, all picked from the suite header:

1. Servers — one or more attached to the suite. Cases can attach their own subsets if they only need part of the surface.
2. Models — the multi-model picker is the whole point. Each model produces its own iteration per case, so you can see where Claude passes and ChatGPT trips.
3. Run all — kicks off every case × every model. Run one from a case row runs just that case.

If Run all is disabled, a connected server is missing, no models are selected, or a run for that suite is already in progress. The header pickers will tell you which condition applies.

Run review

When you click Run on a suite from the Suites landing list, a review sheet opens before the run launches. It shows the suite’s current configuration — clients, iteration count, and settings — so you can confirm or adjust before committing. The run only starts when you confirm in the sheet; closing it leaves the suite unchanged.

Pre-run credit estimate

When enabled on your account, an ⓘ icon appears beside run controls before you launch. Hovering it shows an estimated credit cost for the run about to start — priced against the exact models, cases, and iteration count the button will execute.

The estimate appears on:

• Run all in the suite header — prices every case × model × iterations × run plans.
• Per-case Run buttons in the cases list and case sidebar — prices that case’s configured models for one quick run.
• Run / Run compare in the template editor — prices the currently selected models and the current (possibly unsaved) prompt.
• Swarm journey cards — prices the journey’s next run across its live targets.

The tooltip shows a headline figure and a per-model or per-component breakdown. Copy varies by how well-grounded the estimate is:

Copy	Meaning
Estimated: ~N credits — based on your recent runs	Full coverage, grounded in your own run history
Estimated: ~N credits — partly based on recent runs	Full coverage, partially grounded in history
Rough estimate: ~N credits — improves after first run	Full coverage, heuristic only (no history yet)
At least ~N credits — part of this run is unpriced	Some models or run slices could not be priced
Estimate unavailable for these models	No pricing data available

1 credit = $0.01. Your free daily allowance and any BYOK keys change what is actually deducted. The estimate is informational only — it never blocks or gates a run.

Frozen execution snapshots

The first run of a suite saves the set of MCP servers used as a frozen snapshot; reruns reuse it, so connecting new servers can’t silently change what a suite runs against. Click Update snapshot in the suite header to re-save the current servers and start a new run.

For harness runs, the run’s pinned skills are also frozen at run start and delivered to each iteration from that snapshot — not re-fetched from the live project pool. This means editing a project skill mid-run does not affect iterations already in progress, and the “without skills” A/B arm (configured via skillsOverride: "exclude") runs with no skills regardless of what the project currently holds.

Computer environment

The computer environment picker is only visible when the computers feature flag is enabled on your account and a project is selected for the suite.

In suite settings, the Computer environment select lets you pin a built Docker environment so every eval iteration boots a fresh sandbox from the same image. This keeps results comparable across runs and edits — each iteration gets an identical starting state.

• Choose an environment from the list. Environments that have not finished building are labelled (not built); selecting one will cause the run to fail immediately.
• Choose None (default image) to run without a pinned environment.
• The agent receives a bash tool inside the sandbox.

Once a run completes, the Run detail page shows an Environment row with the name of the environment used. If the environment has since been deleted, the row shows its raw identifier instead so the record remains durable. Hovering the label shows the image template, digest, and provider from the frozen snapshot taken at run time.

Suite execution config

Each eval suite has a Default Execution Config section that controls the model, system prompt, temperature, tool approval, connection settings, capabilities, and host context used when running the suite.

• Model and prompt — Set the default model ID, system prompt, and temperature for all runs in the suite. When running evals against MCP Apps that render widgets, the eval harness automatically enables browser interaction (screenshot, click, type) for any model that supports both vision and tool calling — not just Claude. Models that lack vision or tool calling run without browser interaction.
• Tool approval — Toggle requireToolApproval to pause before each tool call during a run.
• Minimum iterations — Set a floor on how many times each case runs. Every case runs at least this many times, regardless of its own iteration count. Use mcpjam cloud eval update --suite <name> --min-iterations <1-10> to set this from the CLI; off removes the floor.
• Server selection — Servers are not configured here. They come from the suite’s environment. The server picker is intentionally hidden in this editor.
• Save / Reset — Click Save config to persist changes. Click Reset to revert to the last saved state. Unsaved edits are preserved if the page refreshes the config from the server, but are discarded when you switch to a different suite.

Changes to the suite execution config apply to future runs only. Existing run snapshots are not affected.

Personal computers are not available for eval suites. The personal computer toggle and computer-backed tools (such as Bash) are hidden and blocked in the suite execution config editor. If the project’s default host config has a computer attached, resetting a suite to that default automatically strips the computer and any computer-backed tool ids.

A host that grants bash requires a pinned computer environment. If the suite’s host config includes bash (or another computer-backed built-in) but no computer environment is pinned, the run is refused at pre-flight rather than executing with the tool silently absent. Pin a computer environment in suite settings, or remove the computer-backed built-in from the host config.

This applies to every eval run — harness and emulated alike. A single-case run (the Run button on an individual case outside a suite) is always refused for computer-backed built-ins because that surface never provisions a computer; run the case as part of a suite with a pinned environment instead.

How suite defaults apply to test cases

The suite-level system prompt and temperature are runtime defaults: when a test case does not set its own system prompt or temperature, the suite values are used for that iteration. A per-case override always wins — the suite default only fills the gap.

If you have existing suites where test cases do not specify a system prompt, those cases will now run with the suite’s system prompt applied. Cases that already set their own system prompt are unaffected.

CI tab

The CI tab (when enabled for your project) shows only CI-active suites — suites created by the SDK or suites that CI has reported into at least once. Playground-only suites stay in the Evaluate tab. If a project has no CI evals yet, the CI tab shows a quickstart prompt.

The commit rail in the CI tab groups runs by commit SHA and only includes CI (SDK-sourced) runs. Playground runs on mixed suites are excluded from the rail so they don’t appear as spurious manual-commit groups.

Pass Rate vs Accuracy

The metric label shown in run headers, the runs table, charts, and hero stats follows the run’s source, not the suite’s creation source:

• Pass Rate — shown for runs submitted by the SDK (CI runs). Reflects per-case pass/fail.
• Accuracy — shown for runs triggered manually from the UI, via the API, or on a schedule.

On a mixed suite (one that has received both CI and playground runs), the label updates to match the most recent run. Legacy runs without a recorded source fall back to the suite’s creation source.

CI-managed suites

A suite marked CI keeps its configuration somewhere other than this app — either a suite file committed to a repository (mcpjam cloud eval run --file), or a suite the MCPJam SDK created when it reported a run. Those suites are read-only here: name, settings, environments, schedule, models, skills, execution config and cases all refuse edits, in the app and through the API alike, with 409 and details.reason: "CI_OWNED_SUITE_READ_ONLY".

One caller is exempt, and only one: the suite file itself. A write that sends the suite’s own suite.id as declaredSuiteId is the file syncing what it already declares, so it is allowed through — which is how mcpjam cloud eval run --file keeps working. Naming any other id refuses exactly as loudly as naming none, so it is not a way in.

That is not a permission problem, and no role change lifts it. The reason is that an edit made here would not survive: the file sync deletes any case the file does not name, and an SDK suite’s cases are regenerated from the next report. Before this, such an edit lasted until the next CI run and then vanished with nothing recording why.

Two ways forward, both offered on the suite:

• Edit the test file in your repository and run it again. The suite keeps its history and its CI wiring.
• Duplicate to edit. The copy is app-owned and fully editable, and CI can never target it.

Everything that is not a configuration edit is unchanged: run it, replay a run, compare runs, waive a gate, read every setting.

CI-synced test cases

Test cases written by a CI report carry a CI chip next to their name in the cases list. Opening such a case in the editor shows a notice: “Synced from CI — the next CI report may overwrite manual edits.” Manual edits to these cases are preserved until the next CI ingest, which may overwrite them.

Suite deletion

The delete button in the suite switcher is hidden for any suite that is CI-active — either created by the SDK or one that CI has reported into. This protects CI run history; the next CI report would recreate the suite anyway.

Reading results

Suite navigation

Opening the Evaluate tab lands on the Runs view by default, showing run history across all suites with grouped runs, pass-rate changes, and filters. Switch to Suites using the header tabs to see the suites overview. To drill into a suite, click its name; the suite switcher in the breadcrumb lets you jump between suites, create a new one, or delete the current one. If no suites exist yet, the same empty-state hero appears on both the Runs and Suites tabs — click Eval my server: <server name> to open the create-suite form with that server and a name already filled in, or click Create suite to start blank.

Suite view

• Suite accuracy — pass rate of the most recent run, with the last three runs’ trend so you can see whether you’re improving or regressing.
• Run insights — an AI-written diff against your previous completed run: which cases moved, which tools changed behavior, which models diverged. Skim this first; it usually points at the right rabbit hole.
• Runs tab — every run with its summary metrics. Click in for the iteration-level breakdown. The table shows Date first, then Run; suite group rows show a date range and a chevron on the left. Client/model pairings are shown inline per run row; when there are more than two, a +N badge appears — hover it to see all pairings in a tooltip.
• Cases tab — every case with its latest verdict and a quick replay button.
• Executions tab — a flat, filterable list of every individual test execution across all cases, sorted most-recent-first. Each row shows the case name, result (passed/failed/pending/cancelled), and timestamp. Click any row to open it in the compare view.

When you run a suite against multiple host configurations at once, the Runs list groups them into a single collapsible run group row showing mean accuracy and longest duration across all hosts. Expand it to inspect each host’s individual run.

The Runs / Cases segmented control switches between the run history list and the test-cases overview. Performance by Model in the run summary appears only when more than one model was used. To compare two runs, check their boxes in the Runs list and click Compare.

Client and server filters on the Suites tab live in the column headers rather than as separate filter pills.

Where a run came from

Every run carries an origin badge — UI, SDK, API, CLI, MCP, GitHub, Scheduled — and the Source chips above the Runs table filter on it. The filter runs on the server, so an empty result means the project has no such runs, not that they were further down the list.

Two different things go into that badge, and the distinction matters if you are using it as evidence:

• Stamped. The platform decides a run’s source itself, and a caller cannot set it. That is what makes it trustworthy — and also why everything launched through the public API is API: from the server’s side, a CLI run, a GitHub Actions job and an agent’s MCP call are all API calls.
• Declared. The launching process says which of those it is. The CLI declares CLI (or GitHub inside an Actions job, with the commit and job filling the CI column); the hosted MCP worker declares MCP and names the calling agent. Hovering a declared badge says so.

A declared origin is a label, not proof, so nothing is authorized on the strength of it. Alongside both, the platform records the credential the request actually authenticated with — which is what lets the Run by column say via API key ····3f9a under the key owner’s name, rather than making an automated launch look like that person clicking Run.

Cross-host matrix

When two or more host configurations are attached to a suite, a By case / By host toggle appears. By host shows a matrix — one column per host, one row per case. Each cell shows pass/fail dots, pass rate, median latency, and token usage. A host detached after runs were recorded stays visible, labelled historical.

Cost

Every iteration carries the MCPJam-billed cost of the model work it did, priced when the trial finished and stamped with the rates used — so a run’s cost does not move later when prices change. It rolls up onto cases, runs and the metric strip.

A dash (—) means no cost was observed, never that the trial was free:

Why	What you see
Your own API key (BYOK)	MCPJam did not bill it, so there is no cost to report.
A harness run (Claude Code, Codex, Cursor)	A harness turn mixes models — sub-agents on cheaper models under a main one — and the trial’s totals carry no per-model split, so no honest single figure exists. Harness cost arrives with billed attribution.
No token usage reported	Nothing to price.

A cost your own SDK runner reported is shown but labelled runner — it is real, but MCPJam neither computed nor verified it.

When only some of a run’s trials were priced, the total says so. That distinction matters most in CI: a run that looks cheaper may simply be a run we priced less of, which is why the compare API reports coverage counts alongside the cost and a cost gate treats partial coverage as non-gateable rather than as a pass.

Run view

The run header shows a HOLD or SHIP pill for each client/model pairing in the launch. All pairings that share the same decision are grouped into one pill — a single HOLD pill lists every client that did not pass, and a SHIP pill lists every client that did. Intermediate states (Running, Grading, Inconclusive) each get their own pill. The Compare runs and Run again buttons are visible directly in the header.

Below the header, the hero section shows a row per client/model pairing with a pass/fail bar and counts. When a previous launch exists, each pairing row also shows a delta — how many more or fewer cases passed compared to the equivalent pairing in the prior launch. The first launch of a suite shows no deltas.

The Test cases section (formerly the matrix) lists every test case with a search box and Status, Client, and Model filters on one row. There is no master pass/fail bar or “RUN RESULTS” eyebrow label in this section.

• Per-iteration row with case, model, pass/fail, tokens, cost, duration, and the tool calls that actually happened. Each row also shows a one-line summary of where that trial’s user-value chain stopped — for example broke at Tool response, Request satisfied, or chain withheld — so you can scan the table without opening each row.
• Expected vs actual tool calls side-by-side when an iteration fails. For failed iterations, a Categorized diff above the raw Expected/Actual grids groups discrepancies into four categories:
  • Missing — expected tool calls that were never made
  • Extra — actual calls that weren’t expected (reported but non-fatal by default)
  • Out of order — calls that happened in the wrong sequence (when order checking is enabled)
  • Arg mismatch — right tool name, wrong arguments (shown side-by-side)
• User-value chain — when you expand a trial, six numbered stage cards show how far value travelled: Session connected → Tools discovered → Tool selected → Tool called → Response returned → Request satisfied. The card for the first stage that failed opens automatically. Click any card to read what happened at that stage and why; click it again to close. This is shown for every trial — passing and failing alike. A trial that delivered end to end reads as the full delivery story; a failing trial opens on the break.
• Full trace — every turn, every tool call, every token. This is the thing you couldn’t see before; spend time here. When a turn ran through a harness (e.g. Claude Code), the trace detail pane shows an Engine badge — “Claude Code” for harness turns, “Emulated” for turns that ran through MCPJam’s built-in chat engine — so you can tell at a glance which runtime handled each turn. The user-value chain also appears above the transcript in the trace pane, so the answer to “where did this trial stop” is on the same screen as the evidence.
• Per-model breakdown to compare how the same case behaves across models.
• Suggested fixes — after a run completes, a Suggested fixes panel ranks tool-quality and workflow issues by impact. Each issue has a Copy button that copies a ready-to-use fix prompt (tool description + input schema) for a coding agent; Copy top N copies the top issues combined.
• Predicate Gate — when successPredicates are configured on a case, an expandable Predicate Gate section in the iteration detail lists each predicate with a PASS/FAIL verdict, a one-line summary, and the evaluator’s reason. Hidden when no predicates are configured.

Comparing two runs

Select any two completed runs and click Compare. The diff view shows per-case status changes: Passed, Still failing, Regressed (pass→fail), Fixed (fail→pass), New, Removed, and Changed (config differed). Summary metrics show deltas for tokens, cost, and duration.

Case view

• Pass rate across runs — is this case stable, flaky, or trending down?
• Pass rate by model — does this case only work on one model?
• Every past iteration with its trace, so you can A/B a regression against a working run.

Promoting sessions to cases

Any completed chat session can be turned into a test case without rewriting it from scratch. The full conversation is compiled into multi-turn prompt turns, and the dialog lets you pick a destination suite or create a new one.

From the Playground — Open the Sessions rail, hover a session, and click Promote to test case.

From the Swarms tab — Open a completed run, click a session row to select it, then click Promote to test case above the session viewer. The session must belong to a completed run attempt; sessions from in-progress runs show an error in the dialog instead of blocking at submit.

In both cases the dialog shows the servers recorded for that session, lets you set a case title and suite name, and (when attachment pickers are enabled) lets you configure the server attachment and client host for the new suite.

Generating cases from your tools

The Generate button reads your attached servers’ tool catalog and drafts realistic cases — a mix of positive (“call search with a query”) and negative (“don’t call delete_user on a meta-question”). Treat it as a draft: skim, edit the prompts to match how your users actually talk, tighten the checks, then save.

When the suite has a saved server group spanning two or more servers, the generator produces coverage for each server individually plus at least one cross-server case. Suites without a saved server group treat all available servers as a single pool.

Plugin provenance on runs

When a run executed against an environment that pins a plugin, the run detail page shows a Plugins row directly below the environment label. Each chip displays the plugin name and a short bundle hash — the content-addressed identity of the exact bundle the run used.

The bundle hash is what makes two runs of the “same” plugin comparable: a re-import mints a new hash even when the name is unchanged, and an edit changes the hash under an unchanged name. The row is read-only provenance — it records what ran and offers no way to restore or re-pin those versions.

When a run is the “without skills” arm of an A/B compare, a skills excluded badge appears alongside the plugin chips. This distinguishes a deliberately skill-free run from one whose skills failed to load; the plugin’s MCP servers were still connected for that run.

OpenAI submission report

For runs that pinned a plugin, a Submission report button appears in the run header alongside Export traces. Clicking it downloads a Markdown document formatted for OpenAI’s plugin directory review, which asks for five prompts where the plugin should be invoked and three where it must not.

The report is built from the run’s own frozen case records — not from the live suite — so it names the exact bundle hash the run executed. It selects up to five passing positive cases and up to three passing negative cases. When there are not enough passing cases to fill the quota, failing cases are included to reach the count and listed explicitly at the top of the document under Not ready to submit.

The report also flags these conditions as not ready to submit:

Condition	What it means
Fewer than 5 positive cases	The run did not execute enough “should invoke” cases. Add cases to the suite and re-run.
Fewer than 3 negative cases	The run did not execute enough “should NOT invoke” cases. Mark cases as negative tests and re-run.
Failing cases included	One or more selected cases failed; they are named at the top of the document.
No plugin pinned	The run pinned no plugin version, so the report cannot state which bundle was evaluated.
Skills excluded	The run is the “without skills” A/B arm. Submit the arm that includes skills.

The button only appears on runs that pinned a plugin. Plugin-free runs produce no submission document.

Exporting traces

Open a completed run and click the Export traces button (download icon in the run header) to download the run’s traces as an OTLP JSON file. The export uses OpenInference semantic conventions plus mcp.app.* extensions, making it compatible with Arize Phoenix, Datadog, and any other OTLP-compatible observability backend.

Export options

Option	Description
This run	Exports only the iterations from the selected run.
Whole project	Exports all recorded sessions across every run in the project.
Include content & artifacts	Off by default. When enabled, the export includes prompts, outputs, tool arguments and results, and screenshots. Disable this when the content may contain secrets.

The downloaded file is named mcpjam-traces-<scope>-<timestamp>.json.

If the project is too large to export in a single file, use This run scope and export individual runs instead.

What to author first

If you’re new to the surface, the shortest useful loop is:

1. Connect a server in the Inspector.
2. On the Suites or Runs landing, click Eval my server: <server name> to open the create-suite form with that server and a name already filled in.
3. Review the generated cases, confirm the clients and iteration count, then click Run to launch.
4. Open the failures, and decide whether the bug is in your server, your prompt, or the model.

New suites are named Suite 1, Suite 2, and so on — the form picks the next unused number automatically. You can rename the suite at any time.

Alternatively, click Create suite to start from a blank suite and author cases manually:

1. Attach the server you’re shipping.
2. Generate a starting set of cases.
3. Delete the ones that don’t match real usage; tighten checks on the rest.
4. Add the two or three models your users will hit.
5. Run all, open the failures, and decide whether the bug is in your server, your prompt, or the model.

That last step is the one that benefits most from spending time in the trace view.