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

With no annotations, the description carries full burden. It discloses the cost ($0.003 per call), the payment mechanism (x402), and the two-step process. It also states what it checks and that it compares against expectations, making the behavior transparent.

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 a single block but well-structured: it starts with the purpose question, lists checks, then cost and usage. No fluff, each sentence contributes to understanding the tool.

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 complexity of a two-step payment flow and no output schema, the description is remarkably complete. It explains the purpose, the checks, the cost, and the exact call sequence. An agent can correctly invoke this tool without additional context.

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 baseline is 3. The description adds workflow context, explaining that `payment` is a signed x402 payload that completes the purchase inside the call, and clarifies `expect` as expected amount in USDC. This goes beyond the schema's basic 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?

The description opens with a clear question that defines the tool's purpose: verifying whether an Arc payment landed. It enumerates specific checks (payer, recipient, amount in both transfer forms, confirmation, gas) against expectations, distinguishing it from other arc_* tools like arc_contract_check or arc_fee_flow.

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 provides explicit usage instructions: call once without `payment` for terms, sign with wallet, call again with `payment`. It implies this is for verifying payments and contrasts with other tools by focusing on payment confirmation. It doesn't name alternatives but the context is clear.

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