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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds useful behavioral details: results are ordered from cheapest to most expensive, each station includes gasoline and diesel prices, and unrecognized cities produce errors with valid examples. This goes beyond the annotation baseline without contradicting it.

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 concise and front-loaded: the first sentence captures the core functionality, and the Args section is compact. Every sentence adds meaningful information, with no filler or repetition beyond a reasonable inline parameter summary.

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 read-only query tool with two parameters and no output schema, the description is fully adequate. It explains input constraints, output ordering, fuel types returned, and error behavior. The lack of an output schema is compensated by the explicit statement of what is returned.

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 baseline is 3. The description enhances this by giving concrete examples for city ('Madrid', 'paris'), explaining the slug/name flexibility, and noting that errors include valid city examples. For limit, it restates the default and range but adds no new semantics, so the extra value comes primarily from the city parameter context.

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 states the tool returns cheapest gas stations in a specific EkoPump-covered city, sorted by price, with gasoline and diesel prices. This distinguishes it from siblings like get_fuel_prices (broader fuel pricing) and get_active_alerts (alerts). The verb 'Devuelve' and specific resource 'gasolineras... en una ciudad concreta' make the purpose unambiguous.

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?

The description implies when to use it (for city-specific cheap station lookups) and gives constraints (city must be EkoPump-covered, limit 1-25). However, it does not explicitly compare with sibling tools or state when not to use it. The usage context is clear but exclusions and alternatives are absent.

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