web_fetch_tool

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

Despite no annotations, the description provides substantial behavioral details: SSRF hardening (scheme allow-list, private-IP block, per-redirect re-validation), size cap, output sanitization, role-marker stripping, and untrusted wrapping. This goes beyond the basic fetch operation.

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, no redundant words. The purpose is stated first, then detailed safety and output handling. Every sentence provides essential information.

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 the tool's moderate complexity, the description covers core functionality, safety constraints, and output format. With an output schema present, return value explanation is unnecessary. Could mention caching or rate limits but not critical.

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 clear descriptions. The tool description reinforces safety context (SSRF, size cap) that adds value beyond the schema, especially for the url parameter which warns about private IPs.

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 'Fetch a web page by URL and return its main text content', with a specific verb and resource. It distinguishes itself from sibling tools (web_search_tool for searching, metis_verify_tool for verification) by focusing on direct URL fetching.

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?

While the description implies usage for fetching known web pages, it does not explicitly contrast with sibling tools or provide when-to-use vs when-not-to-use guidance. The agent must infer from context.

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