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

Annotations only provide destructiveHint=true; the description goes beyond that by flagging that this MOVES MONEY and settles the authorized amount, which is critical behavioral context. It still omits failure handling, reversibility, and whether partial captures can be repeated, so it falls short of a 5.

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?

Two short clauses, with the money-movement warning front-loaded and capitalized for emphasis, followed by the concrete API endpoint. Every element earns its place with no filler.

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 money-moving mutation with no output schema and sparse annotations, the description covers the essential 'what happens' and 'which endpoint' details. It could still be more complete about idempotency behavior and error/retry semantics for a financial operation.

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 all five parameters, including idempotency_key and metadata, are already documented in the schema. The description only adds that capture can be partial, echoing the amount parameter rather than adding new semantics; baseline 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?

States a precise verb+resource (captures a payment) and the scope of the operation (settles the full or partial authorized amount). It is easily distinguished from siblings like checkout_refund_payment or checkout_void_payment because it explicitly says the payment was previously authorized.

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 phrase 'previously authorized payment' implies the precondition for use, which is helpful. However, it never names alternatives (e.g., refund vs. void vs. capture) or states when NOT to use this tool, leaving routing decisions to inference.

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