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

The description discloses the HTTP method and output format but fails to explain the nine optional parameters or their side effects. The parameter descriptions in the schema are misleading (e.g., 'url' described as 'normalize or cite') and contradict the stated purpose of fetching a URL status, so the tool's actual behavior remains opaque.

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 a single, concise sentence that directly conveys the core functionality. It is appropriately short, though it could benefit from a brief mention of parameters to improve structure.

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 leaves critical gaps: no explanation of the nine parameters, no detail on the return format (e.g., status code only, or additional info), and no clarification of what 'public' entails. Given the tool's apparent complexity (many optional parameters), the description is insufficient for an agent to call it correctly without further inference.

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?

Although schema coverage is 100%, every parameter description appears mismatched with the tool's purpose. For instance, 'ref' is described as a 'Git ref name' and 'city' as a 'public weather hint', which do not relate to HEAD requests. These descriptions add confusion rather than meaning, falling below the baseline for full coverage.

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 action (HEAD), the resource (public URL), and the output (status only). It is specific enough to distinguish the tool's core function, though it could explicitly mention HTTP status code for better precision.

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 no guidance on when to use this tool versus the many siblings (e.g., web-fetch, browser-url-ok, normalize-url). It lacks context about appropriate scenarios or exclusions, leaving the agent to infer usage.

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