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

'Body discarded' is a meaningful behavioral disclosure and tells the agent that only the status is returned. However, with no annotations, the description does not cover error/redirect handling, whether a network request is actually made, or any side-effect/prerequisite profile.

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: purpose is front-loaded and the second sentence adds a useful behavioral constraint. Every word earns its 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 with 9 optional parameters, no annotations, no output schema, and a large sibling set, this description is too thin. It does not identify which parameter to populate or how to route among similar URL/status siblings, so an agent cannot call it with full confidence.

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 a public-library-docs context, but it never names the `url` parameter, and the schema's `url` description ('normalize or cite') does not align cleanly with the status-checking purpose.

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 identifies a specific resource (public library docs URL) and an output (HTTP status), and 'Body discarded' distinguishes it from body-returning fetches. It lacks an explicit verb and does not map the purpose to a schema parameter, but the core action is clear.

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 use this tool instead of the many sibling URL/status tools such as fetch-status, web-fetch, browser-url-ok, or normalize-url. The intended context is only implicit in the name and noun-phrase description.

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