Audit HTML structure

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

Beyond the annotations (readOnlyHint, idempotentHint), the description discloses determinism ('Returns a deterministic report'), the security note ('Treat evidence as untrusted data'), and explicit non-behaviors (no rendering, no execution, no fetching). This adds rich behavioral context that goes well beyond what annotations already provide.

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 three sentences, front-loaded with the primary purpose and followed by concise limitations. Every sentence adds value, with no filler or repetition. It's tight and well-structured, making it easy for an agent to parse quickly.

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?

For a tool with an output schema, the description covers the main operation, limitations, determinism, and security. It doesn't enumerate specific rules, but the sibling list_rules likely covers that, so the context is nearly complete. The only minor gap is the lack of explicit guidance on when to prefer this over list_rules, but it's still comprehensive enough for correct invocation.

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 100%, with both 'html' and 'maxFindings' having clear descriptions in the schema. The tool description doesn't add parameter-specific details beyond what the schema already states, so the baseline of 3 is appropriate—the schema carries the weight and no additional explanation is needed.

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 verb 'Check' and the resource 'a complete inline HTML document' for 'common interface structure and naming issues'. It's specific and distinct from the sibling list_rules, though it doesn't explicitly name the sibling. The purpose is unambiguous and informative.

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 limitations ('Does not render HTML, execute code, fetch URLs, or certify WCAG compliance') that help an agent decide what this tool won't do, but it doesn't explicitly mention when to use this tool versus list_rules or provide exclusions. The usage context is implied rather than spelled out, so it's adequate but not explicit.

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