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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=false, openWorldHint=true), and the description adds genuinely new context: a 24-hour expiry, the Base network, the requirement that the amount be exact and the USDC canonical, and the single-transfer constraint. It does not say what happens on over/underpayment or expiry, but the added behavioral detail is meaningful.

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 dense sentences with the distinguishing point ("Free.") front-loaded and the follow-up call placed last. 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?

With no output schema, the description carries the burden and does well: it tells the agent the order expires in 24 hours, that the response implies an exact amount and recipient to pay, and what to do next. It omits what identifiers the response returns (order id, address shape), which is a minor gap.

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?

Only one parameter (product) and schema description coverage is 100%, so the schema fully documents it. The description adds no meaning about the parameter itself, so 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 specific verb and resource ("Creates a 24-hour order") plus the asset and chain (exact USDC on Base), and names the notion of a "plain USDC transfer order" that contrasts with the sibling buy_file_x402 flow. It never explicitly names that alternative, so an agent must infer the selection boundary rather than read it.

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?

Gives a clear operational sequence: create the order, send exactly that amount in one transfer, then call check_transfer_order with the tx hash. It establishes when to use this tool within the workflow but does not state when NOT to use it or how it differs from buy_file_x402.

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