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

'Non-mutating' largely restates the readOnlyHint=true annotation, though it is a mild reinforcement. The addition of the underlying endpoint POST /v1/us_autocompletions is genuinely new information and hints that the request is a POST despite being a read. No return-shape or cardinality detail is given, but annotations already carry the safety profile.

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?

Three short clauses, each earning its place: purpose first, then the non-mutation note, then the endpoint. No filler and well front-loaded.

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 simple, single-purpose read tool with full schema coverage and readOnlyHint annotations, the description is nearly sufficient; it does not mention the suggestion-list return shape, but with no output schema that is a minor gap rather than a blocking one.

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%, so all four parameters (including the required address_prefix with its example) are already documented in the schema. The description's mention of 'partial primary line' only mirrors that, adding no new semantics; 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 ('Suggest') and resource ('complete US addresses from a partial primary line'), which is clear and non-tautological. It does not explicitly distinguish itself from the closest siblings, verify_us_address or us_zip_lookup, so an agent must infer the autocomplete-vs-verify distinction.

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?

'useful for address entry' implies the usage context but gives no explicit when-to-use, when-not-to-use, or named alternative (e.g., verify_us_address for validation). The usage guidance is implied rather than stated.

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