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

Beyond the annotations (readOnly, idempotent, openWorld), the description discloses SSRF-guarding, boilerplate stripping, return envelope details, follow-redirect behavior, and no API key requirement—all valuable behavioral context that annotations alone don't provide.

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?

Three concise sentences that cover purpose, safety, output, and optional parameters without any fluff. Key information is front-loaded, making it easy to parse quickly.

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 description fully explains the tool's behavior, output fields (including redirects and links), safety measures, and authentication requirements. With no output schema, the listed return fields provide sufficient completeness for an agent to invoke the tool 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 the baseline is 3. The description mentions links and format but doesn't add substantial new semantic meaning beyond the schema. It adequately complements the schema without redundancy.

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 specific verb 'Fetches' with the resource 'any public http(s) URL' and explicitly describes the cleaning and return of content in text/markdown formats. It distinguishes itself from siblings by focusing on fetching a known URL rather than searching or instant answers.

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 implies usage when a specific URL is known and content is needed for an LLM context window, but it does not explicitly compare with alternatives like web_search or state when-not-to-use. Thus, guidance is implied rather than explicit.

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