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

With no annotations, the description carries the behavioral burden, and it does disclose one useful behavior: the response body is discarded. However, it does not describe redirect handling, timeouts, error behavior, or the fact that only the url parameter appears to be the meaningful input.

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 first states the result, and the second states a critical limitation, so both sentences earn their place.

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 whose core operation is fetching a public URL, the description plus the fully documented schema is nearly sufficient. It lacks sibling differentiation and an explicit statement that only url matters, which would be needed to fully guide tool selection and 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?

The schema has 100% description coverage, so the description is not required to re-document parameters. It reinforces that url is the relevant input, but it does not clarify that the other eight optional parameters are effectively ignored rather than being meaningful alternatives.

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 names a concrete operation: it returns HTTP status and content type for a public URL, and clearly notes that the body is discarded. This is specific and understandable, though it does not explicitly differentiate web-fetch from sibling URL-checking tools like fetch-status or browser-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?

There is no guidance about when to prefer this tool over the many URL-related siblings, nor any mention of alternatives or when not to use it. The phrase 'public URL' implies a scope constraint, but it does not help an agent decide between web-fetch and the other similar tools.

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