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

Annotations already indicate read-only, idempotent, non-destructive behavior. The description adds meaningful context beyond those hints: it explains the response is a calendar, never figures, that the detailed response_format counts against the export quota, and that the tool is credit class free. No contradiction with annotations exists.

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 compact but information-dense; every sentence earns its place. It front-loads the return value, then states the input scope, addresses likely user questions, and closes with routing to sibling tools and credit cost. There is no filler or redundant restating of the schema.

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 single-parameter read-only getter with a full input schema and an output schema, the description covers everything an agent needs: what it returns, what it doesn't return, how the parameter affects behavior, related sibling tools, and cost implications. None of the critical context is missing.

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 a well-described enum, so the baseline is 3. The description adds value by explicitly declaring that response_format is the only input and that the answer covers the whole dataset with no narrowing by window or product. It reinforces the parameter's role without relying solely on 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 opens with a precise verb and resource, stating it 'Returns the calendar of the trade data' and enumerates the concrete fields returned. It also explicitly contrasts itself with siblings: 'the CALENDAR, never figures' while routing figure-reading to kyrodata_get_heading_overview. This makes the tool unmistakably distinct from its sibling tools.

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?

It clearly states that the answer covers the whole dataset, so there is no window or product to narrow it with, and that it answers specific questions like 'até quando tem dado?' and 'qual o último mês?'. It also gives explicit alternatives: use kyrodata_resolve_comparison_window for building a like-for-like window and kyrodata_get_heading_overview for reading figures inside it.

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