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

Annotations already declare readOnlyHint and openWorldHint=false, so safety is covered; the description adds cost and auth facts (free, no key) plus the important provenance caveat that these are pairs 'a provider says it serves' and carry per-record verification dates rather than live confirmation. That framing meaningfully shapes how an agent should treat the data. It does not mention result volume, pagination, or what an absent corridor means.

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 short, front-loaded sentences that state content first, then access tier and cost. 'Public tier only' and 'Free, no key' partially overlap, which is the only mild redundancy; nothing else is wasted.

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 three-optional-param read-only lookup with no output schema, the description plus schema gives an agent enough to call it correctly. The residual gap is interpretive: it never says how to read missing corridors (unserved vs undocumented) or how many records to expect, which matters for a 'documented status' registry.

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 coverage is 100% and all three params are optional and documented, so the baseline applies. The description adds only light relational context by tying 'pairs' to from/to and 'per provider' to the provider filter. It does not clarify whether partial filters (from without to) are valid or how filters combine.

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 the resource (cross-border corridors per provider) and enumerates exactly what the record contains: claimed currency pairs, published fees, and last-verified timestamps. That is concrete enough for an agent to know what comes back. It stops short of distinguishing itself from close siblings such as swapeazi_coverage, get_coverage, get_corridor_rates, and corridor_events, so an agent must guess which corridor-related tool to pick.

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?

'Public tier only. Free, no key.' implies the usage context (unauthenticated/preview access), which is genuine routing information. However, there is no explicit when-to-use versus when-not, and no named alternative for the authenticated or rate-focused siblings, so the choice among the many corridor tools is left to inference.

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