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

With no annotations available, the description carries the full behavioral disclosure burden. It does usefully state that the body is discarded, which is a meaningful behavior. However, it does not clarify that most schema parameters appear unrelated or discarded, nor does it explain redirect, error, or authentication behavior. The gap between the simple description and the complex 9-parameter schema is a transparency problem.

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 two short sentences with no filler. The main behavior, including the important 'Body discarded' caveat, is front-loaded. It earns its place and is easy to scan.

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 nine optional parameters, no output schema, and many overlapping sibling tools, a two-sentence description is under-specified. The agent cannot reliably tell which input to use, why the other parameters are present, or how this tool differs from fetch-status and browser-url-ok. The definition is too thin for the actual complexity of the schema.

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%, so the schema already documents the nine parameters and the baseline is 3. The tool description adds only that the operation concerns a public URL, which loosely maps to the `url` parameter. It does not explain which parameter is primary or why unrelated parameters like `city`, `json`, and `zone` exist, but the schema descriptions themselves carry the parameter-level meaning.

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 operation: fetch a public URL and return HTTP status and content type, with the body discarded. It is specific enough to avoid a tautology. However, it does not differentiate web-fetch from similarly named siblings such as fetch-status, browser-url-ok, or playwright-url-ok.

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 'public URL' and 'Body discarded' clauses imply when the tool should be used: for lightweight status/content-type checks where the body is not needed. There is no explicit comparison to alternative tools and no guidance about which of the nine optional schema parameters should be supplied, so the usage guidance remains implicit.

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