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

Beyond the destructiveHint annotation, the description discloses the scheduled nature of cancellation, the exact return structure, the behavior of add-ons during and after the plan ends, and authentication requirements. This adds significant behavioral context that annotations alone do not provide.

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 concise yet complete, with three sentences that each serve a distinct purpose: core action and return, add-on behavior with alternative, and auth requirements. It is well-structured and front-loaded with the primary function.

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 complexity of scheduled cancellation with add-on interactions and permission constraints, the description covers all essential aspects: what happens to add-ons, when cancellation takes effect, return format, and required token scope. It is fully self-contained and complements the sparse annotations and absent output schema.

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 tool has no parameters, so the schema is trivially complete. The description adds no parameter-specific semantics, but none are needed. The baseline for zero-parameter tools is 4, and the description sufficiently explains the operation's behavior and return value.

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 specific action: scheduling the project owner's subscription for cancellation at the end of the current billing period. It distinguishes itself from siblings by explicitly mentioning the timing and the alternative 'unsubscribe_addon' for add-ons, making its purpose unmistakable.

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 provides explicit context for when to use this tool, including owner-only access and billing scope requirements. It also names an alternative (unsubscribe_addon) for stopping add-ons sooner, giving clear when-to-use vs. when-not-to-use guidance.

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