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

Annotations already declare this as read-only, idempotent, and non-destructive, so the safety profile is fully covered. The description adds useful behavioral context beyond the annotations: the exact array structure, that omitting `bank` returns all ten, and that the response surfaces valid bank codes. This is solid additional transparency.

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 sentences, no filler: the first states purpose and output shape, the second explains the optional parameter and discovery mechanism, and the third gives the sibling alternative. Every sentence contributes directly to correct selection and invocation.

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 tool with one optional parameter, rich annotations, an output schema, and a close sibling, the description covers purpose, invocation behavior, alternatives, and return structure. Nothing needed for correct selection or calling is missing.

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 description coverage is 100% and the enum already enumerates all valid codes. The description does add that omitting `bank` returns all ten and that this is also how codes are discovered, but this largely mirrors what the input schema already communicates. The added value is real but modest, so baseline 3 is appropriate.

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 names a specific verb and resource: it returns current policy rates for the ten tracked central banks, and clarifies the output shape as an `interest_rates` array. It also explicitly distinguishes itself from the sibling `get_financial_macro_interest_rates`, so an agent can tell them apart without inspecting schemas.

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?

It states when to use this tool ('Use it for the current rate backdrop') and when not to, by directing the agent to `get_financial_macro_interest_rates` for a single bank's rate path over time. It also explains the omission behavior for retrieving all ten banks, leaving no ambiguity about invocation strategy.

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