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

The description discloses one important behavioral trait: the HTTP body is discarded, so only status and content type are available. However, with no annotations to cover side effects or mutability, a network tool should ideally clarify things like redirects, timeout behavior, or whether the operation is a read-only GET/HEAD request.

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?

Two short sentences with no filler. The primary result is front-loaded, and the 'Body discarded' caveat is valuable and immediately relevant.

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 simple HTTP check, the description covers the main return values and the key constraint of a public URL. However, the unusual 9-parameter schema with unrelated fields is not explained by the description, and with no output schema or annotations, the agent is left to infer error behavior and how strictly the 'url' parameter is required.

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 all parameters are already described individually, including 'url' and the discard behavior of several fields. The description adds only the notion of a 'public' URL and does not explain how the unrelated optional parameters relate to the fetch behavior, but the schema carries the burden.

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 the tool's observable result: HTTP status and content type for a public URL, and clarifies that the body is not returned. This helps distinguish it from siblings like fetch-status and normalize-url, though it uses a noun phrase rather than an explicit verb such as 'returns'.

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?

No guidance is given about when to choose this tool over alternatives. Siblings like fetch-status, browser-url-ok, and playwright-url-ok exist, but the description does not explain when web-fetch is the right choice or when it should be avoided.

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