Compare one pair across every bank

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

The description goes well beyond the readOnlyHint/openWorldHint annotations by disclosing what the call returns (latest rates plus spread stats), how stale quarterly publishers are handled, that missing rates are cross-computed only within the same bank's table, and that banks are never mixed. It even links to a methodology page.

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 dense but well-organized: use case and examples first, then return shape, then edge-case handling, then methodology link. Every sentence adds relevant behavioral info, though it is slightly longer than the minimum needed.

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 no output schema, the description compensates by enumerating the return contents and stats fields, and by explaining staleness and cross-computation rules. It does not spell out the exact JSON shape or what 'covered bank' means, but the methodology link and sibling list_central_banks fill most gaps.

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%, with both source and target fully documented by ISO 4217 patterns and examples. The description reinforces the 'currency pair' concept but adds no new parameter-level meaning beyond the schema, 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?

The description states a clear verb and resource: compare one currency pair across ALL institutions at once. It gives concrete example queries and emphasizes the cross-bank scope, which distinguishes it from per-bank or per-pair siblings like get_official_rates.

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 opens with 'Use this when the user wants one currency pair across ALL institutions at once' and provides example user phrasings. It does not explicitly name alternative tools or state when not to use it, but the use-case framing is clear enough for an agent to route correctly.

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