Runs accessibility, responsive layout, performance, and visual-baseline checks on web or Electron sessions, plus UIA functional assertions and screenshots for native desktop apps.
Run axe accessibility, responsive layout, browser performance or an approved PNG visual-baseline assertion on an existing web/Electron session. Native desktop uses UIA functional assertions and screenshots.
| Name | Required | Description | Default |
|---|---|---|---|
| step | Yes | ||
| sessionId | Yes |
Changes observed during successful MCP inspections.
v0.4.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations mark the tool as destructive and open-world, but the description never says what it destroys or changes. That is surprising for a check tool, so it may resize the viewport or write baselines. It also says nothing about pass/fail semantics, what is returned, or side effects on the session. The word 'approved' baseline hints at a precondition but is not explained.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two dense sentences, front-loaded with the four check types, and no wasted words. The brevity comes at the cost of necessary detail.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
This is a complex, multi-mode tool with a nested schema, no output schema, undocumented parameters and an unexplained destructive annotation. The description leaves out the parameter-to-check mapping, the result format, and how assertion failure is reported.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0% across a nested object with about 15 fields. The description loosely maps 'check' enum values and 'baseline' (PNG). It leaves target, kind='ux', tags, threshold vs maxDiffRatio, maxOverflowPx, minTapTargetPx and maxDurationMs unexplained, including which fields apply to which check type.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
It names four concrete check types (axe accessibility, responsive layout, browser performance, PNG visual-baseline) and says they run against an existing web/Electron session. It also notes that native desktop falls back to UIA assertions and screenshots. It does not set itself apart from siblings like ui_screenshot or test_run.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
'Existing session' implies session_start must run first, and the native-desktop note hints at which checks apply where. There is no explicit guidance on when to use this instead of test_run, ui_snapshot or ui_screenshot, and no exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.