a11y_audit_url

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description is transparent about behavior: it fetches the page, checks specific automatic signals, returns findings by severity, and explicitly disclaims being a full verdict. It also discloses its limited coverage (~1/3 of WCAG), which is crucial for setting expectations.

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 structured with a list of checks and a clear caveat, making it easy to scan. It is slightly long due to the enumeration of WCAG references, but these are informative and not redundant. The length is acceptable given the need to convey scope.

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?

The description covers the tool's purpose, the checks it performs, and the nature of its output ('findings by severity'), plus a limitation note. However, it lacks details about the return format or structure, and parameter descriptions are missing. For the tool's specialized use, it is fairly complete but leaves some gaps.

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 description mentions the URL as the target but does not elaborate on the parameter itself (e.g., expected format). The optional 'lang' parameter is not mentioned at all, despite being defined in the schema with an enum. The description adds no semantic value beyond what the schema already provides.

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 clearly states the tool performs an accessibility audit of a URL, listing specific WCAG criteria it checks. It distinguishes itself from siblings by focusing on automated checks and explicitly mentioning 'Express' in the name, making the verb and scope unambiguous.

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 provides usage guidance by noting 'Filter, not verdict' and that automation covers only ~1/3 of WCAG, implying this is a quick pre-scan rather than a comprehensive audit. However, it does not explicitly contrast it with sibling tools or state when to prefer it, leaving some inference to the agent.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.