x402_submit_payment

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

With no annotations present, the description carries the full disclosure burden. It covers key behaviors: submitting the signed payment, conditional OAuth execution (local callback + remote token exchange), attaching the Bearer token, and returning the merchant's final response. It stops short of explaining error cases, idempotency, or failure modes, but the main behavioral traits are 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?

The description is three focused sentences. The purpose is front-loaded in the first sentence, and each subsequent sentence adds necessary detail about input source and conditional behavior. There is no fluff or repetition, making it appropriately sized for the complexity.

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 tool with no output schema and moderate complexity, the description explains the return value (final response from merchant) and the conditional auth flow. It also ties into the sibling workflow by referencing x402_create_signature. It lacks explicit instruction on when NOT to use it or potential failure scenarios, but it is sufficient for correct summoning in a typical flow.

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 the baseline is 3. The description adds meaningful context beyond the schema by linking payment_signature to x402_create_signature and explaining that sign_mode=centralized_payment triggers OAuth and an Authorization header. This helps an agent understand the relationships between parameters, raising it above baseline.

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 specific verb and resource: "Submit a signed payment to complete a 402-protected request." It clearly identifies the tool's role in the payment flow and distinguishes it from siblings by referencing input from x402_create_signature. The purpose is unmistakable and does not rely on the tool name alone.

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 implies a clear workflow position: "Takes the payment_signature from x402_create_signature" indicates this is used after signature creation. It also notes the conditional handling of sign_mode when set to centralized_payment, aligning with x402_gate_pay_auth. However, it does not explicitly contrast with sibling x402_centralized_payment, so no direct alternatives or exclusions are stated.

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