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

The description discloses a key behavioral trait: NCUA publishes no coordinates, so matching is text-based on city/state/ZIP rather than true distance. It also notes 'Keyless' access. Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the description adds value by explaining the matching limitation beyond what annotations convey.

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 concise and well-structured. It front-loads the main purpose, then gives examples, then states the caveat about coordinates. Every sentence earns its place, with no fluff or repetition. The structure flows logically from 'what' to 'how' to 'limitation'.

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 lookup tool, the description is complete. It states what it returns (address, phone, hours, ATM/drive-thru), gives examples, notes the key limitation, and mentions keyless access. Although there is no output schema, the description describes return fields adequately. Given the tool's moderate complexity and the safety annotations, nothing essential is missing for an agent to call it 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?

The schema covers all 7 parameters with descriptions, so the baseline is 3. The description adds value by providing usage examples, clarifying that the 'name' parameter is fuzzy, and explaining the text-based matching context. This goes beyond the schema's individual parameter descriptions and helps agents understand how to combine parameters effectively.

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 clearly states the tool finds US credit union branch and ATM locations from NCUA records, with a specific verb (find) and resource. It provides concrete query examples and implicitly distinguishes itself from sibling tools like ncua_search_credit_unions by focusing on branch/ATM locations rather than credit union profiles or financials.

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 explicit example queries and notes the text-based matching limitation, which helps agents know when to use it. It doesn't explicitly name alternative tools or when not to use it, but the context is clear enough for an agent to infer its purpose. A minor gap is not listing exclusions, but the examples and caveat are sufficient.

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