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 the body is discarded and that it works on public URLs, which is useful. However, it omits other behavioral aspects such as redirect handling, timeouts, network requirements, or whether it performs any validation beyond URL fetching. The minimal disclosure leaves significant uncertainty.

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 sentence that immediately conveys the core purpose and a key behavior (body discard). It is front-loaded and contains no filler. Every word earns its place.

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, none required, no output schema, and no annotations, yet the description only covers URL fetching. It does not explain the other parameters' purposes or how they relate to the stated function. An agent would be unable to correctly use this tool for anything beyond a simple URL check, leaving significant gaps in understanding the full scope.

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 each of the 9 parameters is described in the schema. The tool description does not add any parameter-specific context beyond the schema, which is acceptable given the high coverage. However, the description fails to explain why parameters like 'city' or 'ref' exist, leaving the agent to infer their role from schema text alone.

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 the tool returns HTTP status and content type for a public URL, which is a specific and actionable purpose. It distinguishes itself from likely siblings by mentioning body discard, though it does not explicitly contrast with similar tools like fetch-status or browser-url-ok. The purpose is clear but not fully differentiated from potential alternatives.

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 on when to use this tool versus alternatives. No mention of conditions, exclusions, or alternatives is present. An agent would have no indication of which tool to choose among the many URL-checking siblings.

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