scan_dom_accessibilityOpens a URL in a headless browser and returns the page's accessibility tree to reveal semantic structure for testing and validation.
Open a supplied URL in a fresh headless Chromium session and return its accessibility tree as structured content.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | Page URL to scan |
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | ||
| snapshot | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations indicate readOnlyHint=true and openWorldHint=true, so the description doesn't need to restate safety. It does add useful context: the session is 'fresh' and 'headless', and the output is the 'accessibility tree as structured content'. However, it doesn't disclose potential pitfalls such as network dependencies, timeouts, or that the tree may not include all DOM elements (e.g., offscreen or hidden).
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?
The description is one concise sentence that front-loads the core action and provides key context (fresh, headless) without waste. It's appropriately sized for a single-parameter tool.
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?
Given the tool has one parameter, a clear output schema, and simple annotations, the description covers the essentials. However, it doesn't specify how to interpret the accessibility tree or whether it includes all ARIA roles, which could matter for downstream use. For a straightforward tool, this is adequate but not exhaustive.
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?
The schema has 100% description coverage for the only parameter (url), so the description doesn't need to re-explain it. The description adds the implication that the URL must be accessible via headless Chromium, but that's minimal added meaning. Thus baseline 3 is appropriate.
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?
The description states a specific action ('scan DOM accessibility') and clarifies it opens a URL in headless Chromium to produce an accessibility tree. It doesn't explicitly contrast with siblings, but the tool name and description are clear enough to distinguish from QA flow and Playwright spec tools.
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?
The description implies the tool should be used when you need an accessibility tree from a URL, but it doesn't provide explicit guidance on when NOT to use it or when to prefer sibling tools. For example, it could say 'use compile_playwright_spec for automated test generation' or 'use dry_run_qa_flow for end-to-end QA scenarios.' Without this, the agent must infer usage from the tool name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.