Get saved beneficiary

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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description adds something the annotations cannot: the result is time-dependent, since validity is evaluated against today's payout rules and can change for the same beneficiary over time. It does not explain what the response shape looks like or what happens for an unknown ID.

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 with no filler; what the tool returns is front-loaded and the rationale for the rule check follows immediately. Every clause contributes information an agent would otherwise have to guess.

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?

With one fully documented parameter and annotations covering the safety profile, the main remaining burden is telling the agent what comes back — which it does (recipient, bank details, validity boolean) despite having no output schema. Only the absence of a described response structure or unknown-ID behavior keeps it from a 5.

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 beneficiaryId parameter is already documented as 'The beneficiary ID to look up'. The description adds no format, prefix, or sourcing detail beyond that, 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 and resource ('Get a saved beneficiary') plus exactly what comes back: recipient details, bank details, and a current payout-rule validity check. It is clearly a single-record lookup, functionally distinct from the sibling list_beneficiaries and create_beneficiary, though it never names those alternatives.

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 second sentence gives a real use context: rules tighten over time, so an older beneficiary may need more fields before it can be paid — implying this is a preflight check before create_transfer. It doesn't explicitly exclude anything or point to siblings, so it falls short of a full when/when-not rubric.

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