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

Beyond annotations (readOnly, idempotent, non-destructive), the description discloses behavioral traits: bounded static checks, no JavaScript execution, no access control bypass, and cache reuse behavior via the fresh parameter. This adds meaningful context regarding what the tool does and doesn't do.

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?

Three sentences, front-loaded with purpose, then constraints, then parameter usage. Every sentence provides necessary information with no repetition or filler.

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?

With an output schema present, return values need no explanation. The description covers purpose, usage constraints, and parameter behavior sufficiently. It doesn't specify what specific accessibility checks are performed, but that is likely detailed in the output schema or result, so the context is adequate.

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 coverage is 100%, so the baseline is 3. The description's parameter guidance ('Pass url as an absolute public HTTP(S) URL', 'Keep fresh=false to allow cache reuse') largely reiterates what the schema already states, adding minimal extra semantic value.

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 opens with a specific verb+resource: 'Run bounded static HTML accessibility checks without a browser.' It clearly distinguishes the tool from siblings like web.url.extract or web.url.performance by emphasizing static HTML, no browser, and public HTTP(S) scope.

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?

It provides clear usage context: 'Use only for public HTTP(S) resources; it does not execute JavaScript or bypass access controls.' This sets boundaries but does not explicitly name alternative tools for dynamic or protected content, though it implies them.

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