pay

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

Beyond the annotations, the description discloses irreversibility, the 402-triggered payment flow, idempotency-key caching behavior, local vs. delegated signing, and balance/mandate constraints. These details are consistent with destructiveHint=true and idempotentHint=true; no contradiction exists.

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 dense yet front-loaded with the most important warning ('SPENDS REAL MONEY'), then the workflow, idempotency behavior, mode selection, and usage guidance. Every sentence carries necessary information without fluff.

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, the description clearly explains the complete payment cycle, idempotency guarantees, both execution modes, and the shape of the result (response plus machine-readable receipt). It is thorough enough for an agent to invoke it correctly and safely.

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 schema covers only 50% of parameters with descriptions, and the description strongly compensates by thoroughly explaining idempotencyKey, agent mode, and the payment path. Method, headers, and body are not detailed in prose, but they are standard HTTP concepts and largely self-explanatory.

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 states a specific action with a critical warning: it spends real money, handles the x402 payment flow, retries the request, and returns response plus receipt. It clearly distinguishes itself from siblings by mentioning 'Use inspect first' and 'Do not use for ordinary unpaid HTTP requests.'

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?

Explicitly tells the agent to call inspect first for pricing and warns not to use this for ordinary unpaid HTTP requests. It also explains the two modes of operation and the server-side mandate restrictions, giving clear when-to-use versus when-not-to-use guidance.

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