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

With no annotations, the description carries the transparency burden. It does disclose one meaningful behavioral trait: 'Page content is not stored.' It also states the output fields. However, it does not explain whether the tool fetches the URL, what happens on failures, rate limits, or why several parameters are marked as discarded.

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 short sentences with the primary behavior front-loaded and no filler. Every word contributes: the first sentence states the output, and the second adds a useful privacy guarantee.

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 required parameters, no output schema, and many closely related sibling tools, this two-sentence description is insufficient. It omits how to choose between the tool and its siblings, and does not explain what role each parameter plays in producing the returned host, scheme, and HTTP status.

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?

The input schema already has 100% parameter coverage, so the baseline is 3. The description adds little parameter-level meaning beyond suggesting that 'a URL' is central; it does not clarify how the city, feed, json, ref, host, or path parameters relate to the stated output.

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 uses a specific verb and resource: 'Return host, scheme, and HTTP status for a URL.' This clearly states the core function. However, the input schema exposes nine very different optional parameters (city, feed, json, ref, host, path), so the description doesn't fully reconcile its narrow 'URL' framing with the tool's actual multi-parameter surface.

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 siblings like fetch-status, normalize-url, web-fetch, or validate-json. The only potential hint is 'Page content is not stored,' which weakly implies a privacy-conscious choice, but no explicit when-to-use or when-not-to-use conditions are provided.

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