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 is covered. The description adds the content shape (title, hierarchy, scope notes) but says nothing about behavior for malformed/unknown codes, rate limits, or whether hierarchical data is truncated — useful additions would have raised this above baseline.

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?

One sentence, zero filler, with the verb and resource front-loaded and the returned fields enumerated after. Nothing to trim.

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 single-required-param read-only lookup with an output schema (so return values need not be documented), the description covers purpose, input meaning, and output contents adequately. The only gap is guidance on how a caller obtains a valid CPC symbol, which is a minor omission for such a simple tool.

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?

Only one parameter and schema description coverage is 0%, so the schema contributes nothing. The description does clarify that 'code' is a CPC symbol (not a patent number or free-text query), which is genuine added meaning, but it gives no format examples or validation rules for the symbol.

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 ('Look up') and a specific resource ('a Cooperative Patent Classification (CPC) symbol'), plus the fields returned (title, parent/child/related symbols, scope-note). This clearly separates it from the patent-oriented siblings (search/detail/recent), though it never names an alternative explicitly, so sibling differentiation is by implication rather than declaration.

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 lookup framing implies when the tool is used (when you already have a CPC symbol and need its taxonomy/metadata), but there is no explicit when-to-use statement, no exclusions, and no pointer to googlepatents_search/suggest for discovering a symbol in the first place. Minimum-viable implied guidance.

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