web_fetch

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

Annotations already mark readOnlyHint and openWorldHint, and the description adds rich behavioral detail: SSRF checks, redirect/byte limits, and the exact return payload (extracted text, quality signals, discovered links, evidence_id, cursor). This goes well beyond the annotations and fully discloses operational constraints.

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, dense sentence front-loads the core purpose and then lists behaviors and outputs in a logical order. Every clause adds value; there is no fluff or redundancy, making it highly efficient.

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?

For a read-only tool with no output schema, the description enumerates all return components (extracted text, quality signals, discovered links, evidence_id, cursor) and key limits (SSRF, redirects, bytes). The agent has enough to invoke it correctly without missing critical information.

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 all parameters are documented. The description mentions cursor continuation and bounded batch, but these are already captured in the schema (e.g., cursor, maxItems). No additional semantic nuance beyond the schema is provided, so the baseline of 3 is appropriate.

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's function: reading one known public URL or a bounded batch, with explicit mention of SSRF checks and output elements. This distinguishes it from the sibling web_search, which is for discovery, by emphasizing 'known' URLs.

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 via 'known public URL' but does not explicitly name web_search as the alternative for finding URLs. It provides context (known URLs) but lacks explicit when-to-use versus when-not-to-use guidance, so it falls at the implied level.

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