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

Annotations declare readOnlyHint=true, so the safety profile is already covered. The description adds the important qualifier that rates are 'indicative' and identifies the rate provider, which is useful context. However, it does not describe return format, rate validity, authentication needs, or other behavioral details, so it remains at the minimum-viable level for an annotated read tool.

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 two short sentences, with the main purpose front-loaded. The second sentence restates the HTTP endpoint, which is largely redundant with the tool name and title, but it is brief and not harmful. Overall efficient with minor waste.

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?

The tool is simple, the schema is fully described, and annotations cover read-only safety. However, with no output schema, the description does not explain what the returned rates look like (e.g. rate format, pair ordering), and it lacks usage guidance. It is adequate but leaves clear gaps for an agent to infer.

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%, so all four parameters are fully documented in the schema. The description adds no parameter-level syntax, formats, or constraints beyond the schema. Baseline 3 is appropriate when the schema does all the heavy lifting.

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 specific verb ('Get') and resource ('indicative foreign-exchange rates Checkout.com uses'), and the parenthetical example ('e.g. for card payouts') further scopes the purpose. It is clearly distinct from all sibling tools, which deal with payments, customers, disputes, and reports.

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 an example context ('for card payouts') but does not state when to use this tool versus alternatives, nor does it include any exclusions or prerequisites. Usage is only implied by the example, fitting the 'implied usage' level.

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