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 only notes 'Body discarded' for the URL response, but says nothing about network access, side effects, error handling, rate limits, or what happens with the other eight parameters. The described behavior is too narrow relative to the actual tool capabilities.

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 (two sentences) and front-loads the URL purpose, but it omits almost all functional scope. It is under-specified rather than efficiently concise; it fails to earn its place because it doesn't convey the tool's actual behavior across nine 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?

Given nine optional parameters, no output schema, and no annotations, the description is severely incomplete. It only explains a fraction of the tool's functionality and leaves an agent without any indication of what the tool does with most of its inputs, making it impossible to call correctly.

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 textual description in the schema. The tool description adds no extra semantic information about parameters. Per the rubric, high coverage warrants a baseline of 3, and the description doesn't deviate from that.

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 purpose: 'HTTP status and content type for a public URL.' However, the input schema accepts nine different parameters (url, city, feed, json, path, zone, query, etc.), each implying a distinct check. The description covers only the URL case and gives no hint about the tool's actual multi-purpose nature, making it misleading about scope.

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 zero guidance on when to use this tool versus the many siblings (fetch-status, normalize-url, browser-url-ok, etc.). No conditions, no exclusions, no mention of alternatives. An agent has no basis to select web-fetch over another tool.

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