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

With no annotations, the description fully discloses critical behaviors: it returns a verbatim 402 challenge, never holds funds, never signs, and instructs the user to use their own client/wallet. This transparency covers side effects and security boundaries comprehensively.

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, with three sentences that flow logically: purpose, usage example, and security warning. It avoids redundancy and maintains a clear structure, earning high marks for efficiency.

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 context: the tool returns payment requirements in the form of a 402 challenge, with guidance on using the output (requirements.accepts[0]) and a concrete example (x402-fetch createPaymentHeader). It lacks an explicit output schema but still provides sufficient operational context.

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 already provides clear descriptions for both parameters (input and service_id) with examples. The description adds marginal value by reinforcing 'specific input' but does not introduce new semantic details beyond the schema's coverage.

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 primary function: obtaining x402 payment requirements for a specific Settlement service input. It distinguishes itself from siblings by emphasizing 'for one Settlement service' and 'specific input you intend to buy', making the scope unambiguous.

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 provides usage instructions (use requirements.accepts[0] to construct payment, never send keys) but does not explicitly compare against sibling tools like army_buy or laen_quote. It implies usage when you have a specific input but lacks explicit alternatives or when-to-use guidance.

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