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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuine value: it discloses the return format ('complete Markdown') and a data-freshness caveat ('Dated examples are not live prices'), which is exactly the kind of context annotations cannot convey.

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?

Two sentences, front-loaded with the resource and scope, then the retrieval instruction. The topic list is long but each item earns its place by mapping to the id enum; 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?

For a no-required-param read tool with no output schema, the description covers the return format and freshness well, but with 0% schema coverage it should explain q's role and whether q combines with id. That omission leaves the retrieval/search contract incomplete.

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 0%, so the description must carry the load. It maps meaningfully onto the id enum (listing the guide topics) and language ('Portuguese and English'), but the q search parameter is never mentioned and its relationship to id is left ambiguous, leaving a real gap.

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 (Find) and resource (Portuguese/English guides to Azores and Madeira fuel prices) and enumerates the topic scope that maps to the id enum. It only softly differentiates from siblings via the 'not live prices' caveat rather than naming get_fuel_prices/get_price_history, so it falls short of a 5.

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?

'Use an article id and language to retrieve its complete Markdown' gives procedural guidance on the id/language path, but there is no explicit when-to-use-this vs the sibling price tools, and the q path is never addressed. Usage is implied rather than routed.

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