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

With no annotations, the description carries the burden and does disclose one important behavior: the body is discarded, so callers should not expect content. It does not disclose output format, side effects beyond a network fetch, or that the schema accepts many non-URL parameters such as city, json, path, and zone.

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 are front-loaded with the core behavior and a useful boundary. It earns a 4 for being concise, though it is arguably too terse for a nine-parameter tool with no output schema.

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 is incomplete for the actual complexity: it has no output schema, no annotations, nine optional parameters, and the schema includes non-URL inputs that are never explained at the tool level. An agent cannot reliably infer how city, feed, json, path, zone, and query relate to the HTTP status/content-type behavior.

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 each parameter has its own description and the baseline is 3. The tool description adds no parameter-level detail, but the schema's per-field explanations like 'discarded after the check' and 'no disk access' carry that 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 clearly states the tool's core output: HTTP status and content type for a public URL, with the body discarded. This gives an agent a specific resource and result, though it does not distinguish it from siblings 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?

The phrase 'for a public URL' implies when to use it, and 'Body discarded' is an exclusion suggesting it is not the tool for retrieving page content. However, no alternative tool is named and there is no explicit when-not-to-use guidance relative to the many sibling tools.

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