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

With no annotations provided, the description carries the full burden of disclosing behavior. The phrase 'Favoritos do dono' conveys no action, side effects, auth requirements, or return handling. It does not even state that the tool returns a list or that 'owner' refers to the authenticated user.

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 extremely brief, but it is a sentence fragment in Portuguese rather than a complete, clear sentence. It under-specifies the tool's function, and the brevity comes at the cost of necessary meaning. It is not 'appropriately sized' because it omits the verb and core behavior.

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 zero-parameter list tool, a complete description would be something like 'List the authenticated user's favorite items.' The actual description only says 'Owner's favorites' and fails to clarify that it returns a list, what the ownership scope is, or any auth context. Since there is no output schema, the description is the only source of behavioral context and it is insufficient.

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 input schema is empty, so there are zero parameters to document. The baseline for 0 params is 4. The description does not need to compensate for any schema gaps, and there is no parameter-related information missing.

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 'Favoritos do dono' ('Owner's favorites') identifies the resource as favorites and adds an ownership qualifier, but it lacks an explicit verb such as 'list' or 'retrieve'. It does not differentiate from sibling list_* tools by itself, leaving the tool name to carry the action. This is clearer than a tautology but still vague as a standalone purpose statement.

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?

No guidance is provided about when to use this tool versus alternatives like add_favorite, remove_favorite, get_library, or other list_* tools. The description gives no context about ownership scope or relation to sibling tools, so an agent has no help selecting this tool over similar ones.

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