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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered; the description adds genuinely new behavioral context: the three coverage tiers, the possibility that a failure rate is not yet published, and that the call is free. It does not explain how tiers are determined or what an 'inferred' result means for downstream use, which keeps it below 5.

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?

Front-loaded with the core purpose and sized reasonably at roughly one paragraph, with no filler sentences. The main weakness is that it is a single sprawling sentence enumerating return fields, which is dense to parse, but every clause carries information.

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?

There is no output schema, so the description must carry the return-value burden, and it does enumerate the returned signals (tier, reconciled outcome count, economics candidates, publishers, error band and type, failure rate) plus the country extension. Gaps remain around interpretation of tiers and the relationship to get_coverage/swapeazi_coverage, but nothing needed to call it correctly 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?

Schema description coverage is 100%, so the baseline is 3. The description does add a little meaning on top: 'for a currency pair and size' links amount to the size band, and the country clause ('e.g. CI for XOF') explains the concrete effect of supplying country — its profile and measured receipts. That is a modest but real addition beyond the schema.

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 resource and scope: evidence coverage for a currency pair and payment size, enumerating what the response contains (tier, reconciled outcomes, publisher count, error band/type, failure-rate availability). An agent can tell this is a data-quality/evidence read rather than a pricing or routing tool. It does not, however, distinguish itself from closely named siblings such as get_coverage or swapeazi_coverage, so it stops short of a 5.

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?

Usage is only implied: the reader infers this is a pre-quote due-diligence check on how well-evidenced a corridor is. 'Free' hints at cost considerations and the country clause hints at an optional extension, but there is no explicit when-to-use, when-not-to-use, or named alternative (e.g. get_coverage).

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