x402_build_payment_payload

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

No annotations provided. Description mentions output goes to X-PAYMENT header but lacks details on validation, side effects, or auth requirements. Minimal disclosure beyond assembly.

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?

Single sentence, 18 words, front-loaded with verb. Every word serves a purpose with no 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?

Given 7 required parameters, no output schema, and no annotations, the description should explain prerequisites (e.g., need a signed authorization) and relationship to sibling tools. It does not.

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 only 14% (only 'value' described as 'Base units'). Description adds no extra meaning for any of the 7 required parameters.

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?

Description clearly states verb ('Assemble'), resource ('x402 paymentPayload'), and source ('from a signed EIP-3009 authorization'), distinguishing it from sibling tools like x402_decode_payment_header.

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?

Implies usage after having a signed authorization, but no explicit guidance on when to use vs. alternatives (e.g., build_transfer_authorization) or preconditions.

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