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

With no annotations, the description carries the burden. It adds valuable behavioral context: 402 is a payment instruction, credits land ~1 block after payment, and the nonce must be preserved. It does not mention auth or rate limits, but the protocol-specific nuance is well disclosed.

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, each earning its place. The description is front-loaded with the purpose and immediately gives actionable next steps and timing. No filler or redundancy.

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?

The description covers the essential protocol flow and timing, and an output schema exists so return values need not be described. However, the lack of parameter info leaves a gap, and without that, the overall completeness is slightly reduced.

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 0% and the description never explains the parameters (usdc_micro, api_key). The name 'usdc_micro' hints at amount, but the description provides no meaning or relationship to the offer.

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 clearly states the tool's function: creating a credit top-up and obtaining an x402 offer. It explains that HTTP 402 is the payment instruction, not an error, and explicitly references the sibling tool pay_x402_invoice, distinguishing this from other tools.

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 description gives explicit guidance on how to use the result: feed accepts[0] into pay_x402_invoice and keep the note nonce. It implies the proper workflow, though it lacks explicit when-not-to-use or alternative guidance.

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