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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety and determinism profile is fully covered by structured data. The description adds essentially nothing beyond that profile — no information about how the service area is determined, what the result means, or any call constraints.

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?

A single front-loaded sentence with no filler or redundancy. 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 one-parameter read-only check, the description is nearly sufficient: the operation, input domain, and safety profile are all clear. The one gap is that with no output schema, the description does not indicate what the result looks like (e.g. a boolean served/not-served answer), which would help an agent interpret the response.

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%; the schema itself specifies '5-digit French postcode, e.g. 75011'. The description adds no format, validation, or edge-case detail beyond the schema, so the baseline of 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?

States a specific verb (check) and a precise resource (whether a French postcode falls in the service area). This is unambiguous and clearly separable from siblings like create_booking, get_quote, or get_services, which are transactional rather than coverage checks.

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?

There is no statement of when to use this tool, no prerequisites, and no mention of alternatives (e.g. whether it should be called before create_booking or get_quote). The only guidance is the implied purpose in the name and title, which is not the same as explicit when-to-use direction.

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