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

Annotations already indicate readOnlyHint=false and destructiveHint=false, and the description only says 'Mutações em assinaturas Guru', which adds no behavioral detail beyond the annotation. It does not explain the lifecycle effect of canceling at cycle end, whether it can be undone, what happens to the subscription in the meantime, or any permissions/side effects. The 'Bulk support' note is useful but insufficient.

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 wastes space by listing 13 different actions that are not all relevant to this specific tool; only 'cancel_at_cycle_end' and the bulk note matter. The 'Flattened action' marker helps, but the extra catalog makes the description noisier and less focused than it should be.

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?

Given the parameter count, lack of output schema, and many sibling mutation tools, the description is too thin. It fails to explain the actual behavior of canceling at cycle end, the meaning of the optional parameters, or the difference from immediate cancellation, leaving the agent to guess or infer from naming conventions.

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?

With schema description coverage at 0%, the description carries the burden of explaining parameters. It does mention 'cancel_at_cycle_end (id)' and 'Bulk support: accepts ids', which clarifies id and ids, but it leaves 'data' and 'account' completely unexplained, and there is no indication whether they are relevant for this action.

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 identifies the specific action 'cancel_at_cycle_end (id)' and includes '[Flattened action: cancel_at_cycle_end]', which helps pinpoint the tool's purpose. However, it opens with a generic list of all subscription mutation actions ('Mutações em assinaturas Guru. Ações: cancel, cancel_at_cycle_end, add_coupon...'), creating ambiguity about whether this tool handles only the flattened action or all listed mutations.

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 explicit guidance is provided on when to use this tool versus alternatives like guru_subscriptions_write_cancel (immediate cancellation) or other mutation siblings. The phrase 'Flattened action' is the only hint that this tool is scoped, but it does not explain the distinction or recommend appropriate usage.

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