web_search

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

With no annotations provided, the description carries the full burden. It discloses meaningful behaviors: auto-selection of CN/international engines, proxy routing for international engines, and fan-out semantics for 'all'. These go beyond the basic schema, though it does not mention output format or rate limits, so it is not exhaustive.

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?

The description is three sentences, front-loaded with the core purpose, and every sentence provides distinct value: purpose, proxy/auto-select behavior, and usage examples. No filler or redundancy.

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 provides sufficient invocation context for a moderately complex tool (3 params, no output schema). It explains engine choices and the proxy routing. However, since there is no output schema, a note about the result format would improve completeness, but the description is still adequate for correct invocation.

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%, so the baseline is 3. The description adds significant meaning to the 'engine' parameter by explaining the 'auto' behavior, the 'all' fan-out, and listing valid values. It does not add detail for 'query' or 'num', but the engine semantics are substantially enriched.

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 opens with a specific verb+resource: 'Search the web across engines.' It clearly distinguishes itself from siblings like fetch_url (fetching a specific URL) and deep_research (presumably deeper analysis). The mention of engine auto-selection further narrows its unique role.

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 gives clear guidance on engine selection: use engine='all' to fan out or specify one of the listed engines. It also explains the auto-selection behavior based on query language. However, it does not explicitly contrast this tool with alternatives like deep_research or fetch_url, so a fully explicit when-to-use is absent.

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