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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is fully covered by structured data. The description's added value is enumerating the payload (description, license, update frequency, tags, resources with formats and URLs), which is genuinely useful given there is no output schema, but it says nothing about lookup failures, rate limits, or freshness of the upstream data.

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?

A single front-loaded sentence that opens with the verb and resource, then lists the returned fields. Every clause carries information and there is no filler, though the trailing enumeration of fields is a long comma chain that could be trimmed.

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 one-parameter read-only lookup with complete annotations and no output schema, the description covers source, input form, and returned content, which is enough for an agent to call it correctly. The only nontrivial gap is error behavior for a nonexistent id, which is minor at this complexity.

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% with an example value, so the schema already documents the single id field. The description restates 'by its id or slug' and reinforces that either form is accepted, which is a small but real addition over the schema text 'Dataset id or slug'; baseline plus a minor lift fits this dimension.

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 a specific verb (Fetch), resource (a single dataset), and source (dados.gov.pt, Portuguese government open data), and enumerates what comes back. It implicitly contrasts with search-style retrieval by saying 'single dataset ... by its id or slug', but it never names a sibling such as dados_pt_search_datasets, so differentiation is inferred rather than stated.

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?

Usage is only implied: the 'by its id or slug' wording signals this is the lookup you use once you already have an identifier, which is meaningful guidance. There is no explicit when-to-use/when-not statement, no pointer to a search tool for discovering ids, and no note on what happens for an unknown slug.

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