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

With no annotations, the description must carry the behavioral burden. It does disclose the HEAD method and status-only output, but the input schema exposes nine optional parameters describing unrelated checks (city, json, query, path, etc.). The description does not explain whether these are alternate uses, ignored, or invalid, nor does it describe response or error behavior. This creates significant ambiguity.

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 that states method, resource, and expected output with no filler. Every word earns its place, though the overall terse-ness hurts completeness rather than conciseness.

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 annotations, and no output schema, one clause is insufficient. The agent cannot tell whether non-URL parameters are alternative modes, ignored inputs, or invalid, nor what 'status' means for each. The schema helps per-parameter, but the description does not unify the tool's 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 the baseline is 3. The description adds HEAD/status meaning for the url parameter, which the schema itself does not state ('HTTPS URL to normalize or cite'), but it adds nothing for the other eight optional parameters. The baseline of 3 is appropriate.

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 operation and resource: 'HEAD a public URL' and clearly states the outcome 'return status only.' This distinguishes it from full-fetch siblings like web-fetch, though it does not explicitly differentiate from URL-checking siblings such as 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?

'Status only' implies a lightweight use case where the caller just needs the HTTP status, and 'public URL' establishes context. However, it never names alternative tools or states when not to use this tool, leaving routing to inference among many sibling tools.

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