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

Adds context well beyond the annotations: data provenance (public OVCCallejero web service), a concrete price ($0.002 USDC per successful call), the payment rails (x402 on Base/Solana/Arc), and the fact failed calls are not charged. That cost and failure-billing model is exactly the kind of information an agent needs before invoking a paid 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?

Three sentences, each carrying distinct load — what it returns, its scope limit, and its payment model — with the core purpose front-loaded. No filler.

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?

Output schema exists and annotations cover the read-only/open-world profile, so the description only needs to add scope, provenance, and pricing; it does all three. Nothing an agent needs to decide whether and how to call it 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%, with both province and municipality documented including the uppercase Spanish-name convention, so the baseline is 3. The description does not clarify the role of the required municipality parameter in a tool that lists municipalities of a province, leaving some ambiguity the schema can't resolve.

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 and resource: a Catastro lookup returning municipalities of a province with their Catastro codes, sourced from the OVCCallejero service. The 'municipality level only' constraint cleanly separates it from property-level tools among the many realestate_* siblings.

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?

Explicitly defines the boundary: municipality level only, and a property-level lookup needs a cadastral reference this tool does not take, which steers an agent away from misuse. It stops short of naming an alternative sibling tool, so it is slightly 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.