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

With no annotations, the description carries the full burden of behavioral disclosure. It communicates that the tool returns all supported corridors and optionally provides live trip volume for a specific corridor. It does not mention side effects, but the description clearly frames this as a read-only lookup and adds useful context beyond the raw schema.

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 sentences with no filler. The core purpose is front-loaded, and the optional parameter behavior is stated in the second sentence. Every word earns its place.

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 simple corridor-listing tool with no output schema, the description covers the main outcome: all supported corridors, optional filtering by one corridor, and live trip volume. It does not detail the response format or whether both country parameters are required together, but the description is sufficiently complete for an agent to invoke it correctly in most cases.

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%, so the parameters are already documented as ISO-3166 alpha-2 country codes. The description adds meaningful value by explaining that these parameters are optional and that combining them scopes the result to a single corridor with live trip volume. This goes beyond the schema's field descriptions.

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 clearly identifies the resource as supported Europe ↔ Africa corridors and adds the optional live trip volume scoping. It lacks an explicit verb like 'list' or 'returns,' but 'Every supported...' strongly implies a retrieval operation. The corridor focus distinguishes it from sibling tools that deal with cities, couriers, or quotes.

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 explains when to supply parameters ('Optionally scope to one corridor for live trip volume'), which gives some usage context. However, it does not mention alternatives among the sibling tools or state when this tool should be preferred over get_cities or get_services. Guidance is implied rather than explicit.

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