ContextFetch find similar pages

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

Annotations establish that this is a read-only, open-world call, so the safety profile is covered. The description adds real behavior beyond that: results exclude the source domain, and the return payload is titles, URLs and the most relevant passages rendered as Markdown. That return-shape disclosure is genuinely useful and not present in the structured fields.

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?

A single sentence that front-loads the core action, adds intent examples in a compact parenthetical, and closes with the return format. Nothing is wasted and no backtracking is required.

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?

There is no output schema, and the description compensates by summarizing the return payload. For a two-parameter read-only lookup tool with full annotation coverage, an agent has enough to call it correctly; only pagination/truncation limits for the passage text are left unstated.

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% with both parameters fully documented, including the 1-25 range and default for num_results, so the schema does the heavy lifting. The description mentions the URL input implicitly but adds no format constraints or extra meaning beyond what the schema already states, making the baseline 3 correct.

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?

States a specific verb+resource: finding pages similar to a given URL, with parenthetical examples of the intent (alternatives, related docs, competing libraries). This clearly distinguishes it from contextfetch_search and contextfetch_extract_url in spirit, though it never names a sibling explicitly, which keeps it just short of a 5.

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 examples ('alternatives, related docs, competing libraries') imply when the tool is useful, and the source-domain exclusion hints at intended use. However there is no explicit comparison against the many sibling search/research tools, nor any stated preconditions (e.g. URL must be public/crawlable), so usage is only implied.

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