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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile (safe read against an open dataset) is covered. The description adds that classification data is retrievable 'at any level' and lists the returned fields, which is modest added context. It does not add auth, rate-limit, or freshness information beyond annotations, so a 3 is appropriate.

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, zero filler. The primary purpose and payload are front-loaded, and the sibling routing is packed into a single trailing sentence.

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?

An output schema exists, so return-value shape need not be re-explained, and the description covers purpose, scope, and routing. For a one-parameter read tool this is essentially complete; only minor edge details (e.g., valid symbol formats or hierarchy depth nuance) are left to the schema.

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% and the single 'code' parameter is fully documented in the schema. The description only restates that input is a CPC symbol, adding no syntax, format, or hierarchy-level detail beyond what the schema already provides, so the baseline 3 applies.

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 (Fetch) and resource (official classification records for a CPC symbol) and enumerates the payload it returns (title, parent/child/related symbols, scope note). It also names the sibling tools it is not, so an agent can distinguish it from search/detail/coverage without opening a schema.

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?

Explicitly routes the agent: use googlepatents_search for patent documents, googlepatents_detail for one patent, and googlepatents_coverage for country/year totals. This is textbook when-to-use-this-vs-alternatives guidance with no inference required.

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