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

With no annotations, the description carries the full burden. It discloses that 'Page content is not stored,' which is a behavioral note, but it does not explain other behaviors such as whether it makes a network request, rate limits, or how the many other parameters are handled. The schema hints at shape checks but the description does not elaborate.

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 two short sentences, front-loaded with the core purpose. Every word serves a purpose, and it is appropriately concise for a simple tool.

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 9 optional parameters, no required parameters, and no output schema, the description is incomplete. It does not explain how to invoke the tool (which parameters to provide), what the output format looks like, or whether the other parameters are ignored. The description only covers a URL scenario but leaves the rest ambiguous.

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 does not add meaning beyond the schema; it does not clarify that only the 'url' parameter is relevant and the others are decoys or discarded. The schema already describes each parameter, but the description fails to guide which to use.

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 states a clear purpose: 'Return host, scheme, and HTTP status for a URL.' This is a specific verb and resource. However, it does not explicitly distinguish itself from siblings like 'fetch-status' or 'web-fetch,' which may also return HTTP status, so it loses a point for missing explicit differentiation.

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 on when to use this tool versus alternatives. The description does not mention any conditions, exclusions, or mention of sibling tools. An agent has no information about whether to choose this over 'fetch-status' or 'normalize-url'.

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