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

Annotations are absent, so the description bears the full burden. It discloses that page content is not stored, which is useful, but it omits critical behaviors: whether network requests are made, error handling, rate limits, or what happens with the non-URL parameters. The schema descriptions mention 'discarded after the shape check' for many fields, but the tool description doesn't explain this pattern, leaving behavior opaque.

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 sentences with no wasted words; the key output and a privacy note are front-loaded. The description is appropriately brief, though it lacks essential scope details.

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?

This tool has nine parameters, no annotations, and no output schema. The description only covers a narrow URL-focused behavior and completely ignores the other parameters, their purpose, and how they relate. An agent cannot know what the tool actually does with city, feed, json, etc., or when to invoke it. The description is severely inadequate for the tool's complexity.

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 a clear schema-level explanation. However, the tool description adds no meaning beyond that and directly conflicts with the schema by focusing solely on URL while many parameters (city, feed, json, path, zone, query) are unrelated. The description does not help an agent understand which parameters to supply or how they interact with the stated 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 states a specific verb and resource ('Return host, scheme, and HTTP status for a URL') and a key differentiator (page content not stored). However, the input schema includes nine unrelated parameters (city, feed, json, etc.), which muddles the stated purpose and makes it unclear whether the tool actually does more than URL analysis. It doesn't explicitly contrast with siblings like fetch-status or normalize-url.

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 on when to use this tool versus the many siblings (e.g., fetch-status, normalize-url, browser-url-ok). The description gives no use cases, exclusions, or alternatives, leaving an agent to infer the appropriate context from the name and short description alone.

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