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

Annotations already declare destructiveHint=true and readOnlyHint=false, but the description adds what those annotations cannot: that the action is irreversible, that it triggers a refund, and that token validation failures (missing/expired/used) cause rejection. That is material behavior beyond the structured fields.

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?

Three sentences, front-loaded with the irreversibility and role in the flow, then prerequisites, then the pointer to the policy sibling. No filler or restated field names.

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 destructive three-parameter tool with an output schema and full annotation coverage, the description supplies everything an agent needs: ordering, prerequisites, failure modes, and reversibility. Return-value details are correctly omitted since an output schema exists.

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%, so the baseline is 3, but the description adds lifecycle semantics the schema only hints at: the token is single-use, is delivered by email via request_cancel_token, and is rejected if expired or consumed. These constraints meaningfully shape invocation beyond the field descriptions.

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?

States a specific verb ('cancels'), the resource ('a booking'), the side effect ('starts any refund due'), and its position in the two-step flow. An agent can distinguish it from request_cancel_token and get_cancellation_policy without opening any schema.

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 says this is the second of two steps, names the prerequisite producer (request_cancel_token), describes the required input provenance (emailed token), and identifies the sibling (get_cancellation_policy) for refund terms. Rejection conditions for the token also act as explicit when-not guidance.

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