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

Annotations already set destructiveHint=true, and the description reinforces this by stating 'Irreversível' (irreversible). It additionally discloses bulk support behavior, which goes beyond the annotations. There is no contradiction.

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 concise: two sentences. The first sentence covers purpose, requirement, and irreversibility. The second adds bulk support. There is no redundant or unnecessary text.

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 cancellation tool with three parameters and no output schema, the description covers purpose, required parameter, irreversibility, and bulk capability. It lacks explanation of the account parameter and potential error conditions, but is largely complete given the tool's simplicity.

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 has three parameters (account, invoice_id, invoice_ids) with 0% description coverage. The description adds meaning for invoice_id (required) and invoice_ids (bulk), but ignores the account parameter. This partial compensation results in a baseline of 3.

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 verb 'Cancela' (cancel) and the resource 'fatura' (invoice), specifying the Pagar.me V5 platform and the required invoice_id. It distinguishes itself from siblings like pagarme_invoices_get or pagarme_invoices_write by being the cancel operation.

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 mentions that invoice_id is required and that bulk execution is supported via invoice_ids. However, it does not provide explicit guidance on when to use this tool versus alternatives or when not to use it (e.g., prerequisites, state of invoice). Usage is implied but not fully elaborated.

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