x402_verify_payment

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

With no annotations, the description carries the full transparency burden. It conveys the core behavior (confirming payment received) and the context (incoming, before access), but does not disclose details like on-chain checking, confirmation requirements, or potential side effects. This is a reasonable but not deeply transparent description.

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 concise, two sentences, and front-loaded with the primary purpose. Every word adds value, and it efficiently communicates both the action and the usage context.

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 simple verify tool, the description provides clear purpose and usage, but it lacks any indication of return value or success/failure semantics. Given no output schema, the description should mention what the caller can expect (e.g., boolean confirmation, error on invalid hash). This gap prevents a higher score.

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?

The input schema already provides detailed descriptions for all three parameters (100% coverage), including the source of txHash from the X-Payment-Proof header. The tool description itself adds no additional parameter-level meaning, so the baseline score of 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?

The description clearly states the tool verifies an incoming payment transaction, with a specific verb and resource. It further distinguishes its purpose by tying it to granting access to a paid resource, which differentiates it from sibling tools like x402_tx_status.

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 clearly indicates when to use the tool ('before granting access to a paid resource'), providing strong contextual guidance. However, it does not explicitly mention when not to use it or cite alternative tools, so it stops short of full exclusionary guidance.

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