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 useful, but it does not clarify whether the tool makes network requests, requires authentication, has rate limits, or what happens with the other parameters. For a tool that likely performs HTTP checks, this is insufficient.

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, concise sentence that front-loads the primary purpose and includes a relevant note about not storing content. It is efficient and has no fluff, though it may be too terse to fully cover the tool's behavior.

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 parameters, no output schema, and no annotations, this description is incomplete. It focuses only on 'URL' and ignores the other 8 parameters, leaving their role unclear. It also does not explain return format or any edge cases, making it hard for an agent to call correctly in all contexts.

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 all 9 parameters are documented in the schema. The tool description adds no extra meaning beyond the schema, but it also does not contradict it. Since the schema already provides descriptions, a baseline of 3 is appropriate; the description does not enhance parameter understanding.

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 clearly states a specific verb and resource: returning host, scheme, and HTTP status for a URL. It is distinct from sibling tools like normalize-url or fetch-status, but it does not explicitly name them, so it only partially differentiates. The core purpose is unambiguous.

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 on when to use this tool versus the many sibling tools (e.g., browser-url-ok, fetch-status, normalize-url). The description only states what it does, leaving the agent to infer suitability. There is no mention of exclusions or alternatives.

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