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

With no annotations, the description carries the full behavioral burden. It clearly discloses that the body is discarded and indicates the two return fields (HTTP status, content type). It does not mention redirects, error handling, or how the other eight schema parameters relate to the fetch, leaving ambiguity.

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?

Two sentences with no filler; the core function is front-loaded and the secondary behavior ('Body discarded') is stated separately. 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 optional parameters, no annotations, and no output schema, yet the description only covers URL fetching. It does not clarify whether `url` is required, what the other parameters do, or how this tool relates to sibling status-check tools, so an agent cannot confidently invoke it in all intended 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 reinforces that `url` is the key input by mentioning 'a public URL', but it adds no detail about the other parameters or which are applicable, and the schema marks none as required.

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 the tool returns HTTP status and content type for a public URL and explicitly notes the body is discarded. This is a specific and understandable outcome, though it lacks a verb and does not differentiate from sibling tools like fetch-status or browser-url-ok.

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 scopes usage to 'public URL' and warns 'Body discarded', implying it should be used when only status and content type are needed. However, it does not name alternatives or provide when-not-to-use guidance, leaving selection among siblings to inference.

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