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

With no annotations, the description must carry the behavioral burden. It discloses that 'Page content is not stored,' which is useful, but it does not mention that the tool likely performs network requests, what happens on failure, or that it has multiple check modes (e.g., city, JSON, path). The parameter descriptions mention 'discarded' and 'no disk access,' but those are in the schema, not the description, and are not sufficient for a tool with no annotation coverage.

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 with no wasted words. It front-loads the primary function and adds one behavioral note, which is efficient.

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 annotations, no output schema, and a description that only covers one function. It lacks details on return values, error handling, prerequisites, and the purpose of the other parameters. For a tool with this complexity, the description is far from complete and would not enable an agent to call it correctly for non-URL cases.

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 baseline is 3, but the description's stated purpose ('host, scheme, and HTTP status') does not align with the 9-parameter schema that includes city, feed, JSON, path, zone, and query. The description misrepresents the tool's actual scope, and while the schema documents each parameter, the description adds no context about why these unrelated parameters exist. This mismatch could mislead an agent into using the tool for the wrong 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 ('Return') and resource ('host, scheme, and HTTP status for a URL'), which is clear and distinct from siblings like web-fetch or normalize-url. However, it does not explicitly differentiate from fetch-status or normalize-url, and the description's narrow purpose clashes with the broad schema, slightly reducing clarity.

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 vs alternatives. It does not mention when not to use it, nor does it reference siblings like fetch-status, web-fetch, or normalize-url. An agent would have to infer usage from the schema, which is not sufficient given the wide parameter set.

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