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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds '(personal data)', a useful note that the payload carries PII, and the endpoint mapping, but says nothing about permissions, error behavior, or response shape.

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 short front-loaded fragments with no filler; the identifier-based scope and PII note land immediately. The REST route is slightly redundant with the tool name but helps agents map to API docs.

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 one-parameter read with no output schema, the description should at least sketch what comes back (candidate record fields) or what a missing id yields. It gives a high-level 'one candidate (personal data)' but leaves the return contract and failure mode unspecified.

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% and the single parameter is documented in-schema as 'CATS candidate id' with a positivity/range constraint. The description adds nothing beyond that, which is the expected baseline when the schema already does the work.

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+resource: fetch one candidate by id, plus the underlying REST route GET /candidates/{id}. The 'by id' scope implicitly separates it from cats_list_candidates, cats_filter_candidates, and cats_search_candidates, though no sibling is named explicitly.

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?

'by id' signals the required input and thus implies the lookup-by-identifier use case, but there is no explicit statement of when to prefer this over the filter/search/list siblings, nor any prerequisite or error expectation (e.g. what happens for an unknown id).

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