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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so safety is covered. The description adds real value beyond that: "Free, no account needed" discloses the auth requirement, and it spells out the return shape (ranked sections, page and heading title, heading-anchored url, leading snippet). It does not mention empty-result or rate-limit behavior, so not a 5.

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?

Front-loaded with the access constraint then purpose, followed by examples, return shape, and the sibling redirect. Dense but every sentence carries distinct information; no filler.

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?

No output schema exists, and the description compensates by enumerating what each result contains (rank, page, heading, url, snippet). With annotations covering safety and the schema covering both params, an agent has everything needed to call this 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 coverage is 100%, so both parameters are already documented with types, bounds, and defaults. The description adds meaning for `query` by showing natural-language question examples, but says nothing about `limit` or result-count tradeoffs, so it stays at the high-coverage baseline.

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?

Specific verb+resource ("Search the three.ws documentation") with concrete example queries that pin down the granularity of results (sections, not pages). It explicitly names the sibling it is not: "to browse ready-made 3D assets call search_catalog instead."

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?

Gives explicit when-to-use ("Use this before guessing at an API or a flow") and an explicit alternative with its selecting condition (search_catalog for ready-made assets). Nothing is left to inference about which tool to pick.

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