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

Annotations only give destructiveHint=true, so the description carries the behavioral load and does so richly: irreversibility, single-display of card details, no re-draw (second call returns already_retrieved), null-field handling, and AVS billing-address semantics. This is well beyond what the annotation provides and consistent with it.

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?

Dense but front-loaded: the exactly-once rule and immediacy of storing details come first, followed by return fields and billing/AVS guidance. Length is justified by genuinely non-obvious constraints, though a few clauses (e.g., the shipping-address aside) run long.

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?

No output schema exists, yet the description enumerates the returned fields (card number, expiry, CVC, cardholder_name, billing_address components) and how to use them. Combined with the usage and irreversibility rules, an agent has everything needed to call and consume the result correctly.

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 description coverage is 100% and there is a single required parameter, so the schema already documents request_id fully. The description references the approved request but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 (draw/return) and resource (single-use virtual card) scoped to an APPROVED purchase request. It clearly separates itself from check_status by naming it for status polling, so an agent can distinguish it from siblings without opening schemas.

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?

Explicit when-to-use ('only when you are ready to pay'), when-not ('do NOT call this speculatively, to poll status (use check_status for that), or more than once'), and the alternative for the pre-approval case. The exactly-once constraint and the not-yet-approved path are both spelled out.

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