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

With no annotations provided, the description carries the full burden of disclosure. It does reveal the HTTP method (HEAD) and that only status is returned, which is useful, but it does not disclose that inputs are 'discarded after the shape check' (as the schema hints for most parameters), what status values look like, or that the tool accepts non-URL inputs at all. The behavioral model is under-described for a tool with nine possible inputs.

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, front-loaded sentence with zero filler—'HEAD a public URL and return status only' communicates the core operation efficiently. While very concise, it is arguably too terse for a tool whose schema exposes nine heterogeneous inputs, so it is not fully appropriately sized.

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?

Given no annotations, no output schema, nine parameters, and 27 siblings, the description is incomplete. An agent still cannot determine which parameter to pass, what the status response looks like, or how this tool differs from status-catalog and web-fetch for a URL status check. The one-line description does not equip the agent to invoke the tool correctly across its declared input surface.

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 baseline of 3 applies even though the description adds no parameter detail. The description implies the 'url' parameter is the primary input, but it does nothing to clarify how the other eight parameters map to the 'HEAD a public URL' behavior—if anything, the schema's url description ('normalize or cite') conflicts with HEAD semantics, and the description offers no reconciliation.

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 specific verb and resource—'HEAD a public URL'—and limits the result to 'status only,' which reads as a clear liveness/status check. However, the input schema accepts nine unrelated parameter types (city, json, ref, feed, path, zone, query, host) whose descriptions all point to shape-check/discard behavior, so the stated purpose covers only one of the tool's apparent input modes. The mismatch between the narrow description and the wide schema makes the overall purpose ambiguous.

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 for when to use fetch-status versus its many siblings such as web-fetch, browser-url-ok, playwright-url-ok, normalize-url, or status-catalog. An agent cannot tell from the description whether this is the lightweight safe probe or the fallback shape checker; the one-liner provides no when/when-not conditions.

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