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

Annotations already label the tool as destructive, but the description adds valuable specifics: it releases held inventory, cancels the Stripe PaymentIntent if not yet captured, and requires authentication. These details are not in the annotations and help the agent understand the full impact. No contradiction with annotations.

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 (two sentences), front-loaded with the primary action, and contains no irrelevant information. Every sentence contributes meaningful detail.

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 destructive nature and the existence of an output schema, the description covers the essential aspects: what it does, its side effects, and authentication requirements. It lacks explicit caveats (e.g., cannot be used on completed sessions), but overall is quite complete for a cancellation tool.

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 already provides clear descriptions for both parameters (checkout_id and bearer_token) with 100% coverage. The tool description adds no additional parameter semantics, so the baseline score of 3 is appropriate.

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 uses a specific verb ('Cancel') and resource ('in-progress checkout session'), clearly distinguishing it from sibling tools like checkout_complete and checkout_create. It also explains the key side effects, leaving no ambiguity about its function.

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 clear context for when to use the tool: canceling an in-progress checkout that has held inventory and a pending PaymentIntent. However, it does not explicitly mention alternatives or situations where this tool should not be used, so it falls short of a 5.

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