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

With no annotations, the description must carry the behavioral load; it discloses the return fields and the cost hint 'One API call', which is genuinely useful. However, it says nothing about whether the call is read-only, permission needs, rate limits, or failure behavior for unsupported territories (e.g. Canary Islands, Navarra), leaving real gaps for an unannotated 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?

Four compact fragments, front-loaded with what the tool returns before the usage constraint. Every clause carries information; nothing is repeated from the title or schema.

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 single-parameter read tool with full schema coverage and no output schema, the description covers scope, value source, returned fields, and call cost. It stops short of explaining matching behavior for the province string or what happens outside the common territory, which would matter for correct invocation.

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 the single parameter is already documented with a format example, so the baseline is 3. The description adds value by tying the value to list_provinces and by restricting the accepted values to common-territory provinces, which the schema alone does not convey.

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 exact resource (municipalities of one Spanish province) and states what comes back (cadastre code, INE code) plus the geographic scope (Spain only, common territory). It is distinguishable at a glance from the sibling list_provinces, which supplies provinces rather than municipalities.

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?

'Take the province name from list_provinces' establishes the prerequisite call and the correct value source explicitly, and 'Spain only (common territory)' excludes unsupported regions. It does not spell out a when-not-to-use case or an alternative tool, so it falls short of a 5.

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