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

Annotations already declare readOnly, idempotent, and non-destructive, and the description adds context by explaining the aggregated summary behavior when country is omitted. It also enumerates the data types covered, clarifying what 'coverage' means without contradicting annotations.

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: two sentences plus an Args block, with the core function stated upfront. The Args block is somewhat redundant with the schema, but the overall length is appropriate and contains 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?

There is no output schema, so the description carries the burden of explaining return behavior. It states it returns the types of live data available per country, which is sufficient for a simple lookup tool, though the exact return format (e.g., list of strings) is not specified.

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?

The schema fully describes the country parameter (ISO code, optional, omitted behavior) with 100% coverage, providing a baseline of 3. The description's Args section repeats this but adds an example ('PT'), offering a minor enhancement beyond the schema.

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 live data coverage types per country (or all countries), listing eight data categories (e.g., combustible, transporte público). It distinguishes from sibling tools that focus on specific data types by being a coverage overview for a country. The verb 'Devuelve' plus resource makes 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 provides explicit use cases, such as answering whether EkoPump has data for a country or what it covers in Portugal. It explains the optional country parameter's behavior (aggregate summary when omitted). However, it does not directly state when not to use this tool versus sibling tools.

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