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

With no annotations, the description carries the full burden of behavioral disclosure. It adds one useful note ('Page content is not stored') but omits critical behaviors: it does not mention that many parameters are discarded (as stated in the schema), whether any side effects occur, or any rate limits or auth requirements. This is minimal for a tool with 9 parameters.

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 sentences, with the primary action front-loaded. It is efficient and free of fluff. However, it is arguably too terse given the tool's complexity, but conciseness itself is well-executed.

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?

The tool has 9 parameters, no output schema, and no annotations. The description covers only the URL-related behavior and ignores the other parameters entirely, offering no explanation of when or why to use them. This is insufficient for an agent to correctly invoke the tool beyond the URL case.

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 already has a meaningful description in the schema. The tool description adds no parameter-level information, but the schema itself is rich enough (e.g., 'discarded after the shape check'). The baseline of 3 is appropriate; the description does not mislead but also does not compensate for any gaps.

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 ('Return') and resource ('host, scheme, and HTTP status for a URL'), which is unambiguous for the URL aspect. However, it does not mention the tool's broader parameter set (e.g., ref, city, feed) or differentiate from siblings like fetch-status or normalize-url, so it is not fully complete.

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?

The description provides no guidance on when to use this tool versus alternatives such as fetch-status, browser-url-ok, or normalize-url. It only states what it returns, leaving the selection decision entirely to the agent without any comparative context.

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