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

With no annotations, the description must carry the full behavioral burden. It discloses one key behavior: 'Body discarded.' This tells the agent that the body is not returned, which is useful. However, it does not mention that many other parameters (ref, city, feed, etc.) are also discarded or that no disk access occurs. The schema descriptions partially cover this, but the description itself is sparse and omits most behavioral nuances.

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 extremely short (one sentence), but it is under-specified rather than concise. It omits critical information about the tool's broader scope and side effects. It is not appropriately sized because it fails to cover the tool's actual functionality for the majority of its parameters.

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 and no output schema, yet the description only addresses the URL use case. It leaves the other 8 parameters entirely unmentioned, making it inadequate for an agent to understand the tool's full capabilities. Even for the URL case, it does not describe the response format or any edge 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 coverage is 100%, so the baseline is 3. The description adds a small qualifier: 'public URL' implies the URL must be publicly accessible, which is not explicitly in the schema. But it does not elaborate on the other parameters, so it adds minimal semantic value beyond the schema.

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: 'HTTP status and content type for a public URL.' This is a specific verb and resource, so an agent can infer what it does for the URL case. However, it does not differentiate from sibling tools like fetch-status or browser-url-ok, and it ignores the tool's other 8 parameters, so it is only partially 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?

There is no guidance about when to use this tool versus alternatives. It does not mention any exclusions, prerequisites, or preferred contexts. An agent has no basis for choosing web-fetch 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.