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

Annotations already cover mutation and open-world traits, but the description adds substantive context: charging only occurs after 'code checks the answer', and an unpaid call returns payment terms instead of an error. It omits failure/refund behavior and whether repeated calls re-charge, which are the remaining risks for a paid operation.

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 first sentence is well front-loaded and dense with meaning, but the nine-entry action enumeration repeats 'sold per call by Taifoon at ... USDC (x402)' verbatim each time, roughly tripling the length for the same information.

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 3-parameter tool with no output schema, the description covers the payment handshake, per-call costs, and the alternative tool. It stops short of describing what a successful response contains or what happens on a rejected/underpaid call.

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 baseline is 3, but the description adds decision-relevant pricing per action value (0.001–0.027917 USDC), which the schema does not carry. Minor gap: the schema promises each class 'lists its example in the action list', yet the description lists only prices, not per-class input examples.

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?

States a specific verb and resource ('Buys one call of a skill the layer sells per call (x402)') and explicitly distinguishes itself from the sibling taifoon_hire. An agent can tell this is the pay-per-call purchase path versus the job-hiring path without opening any schema.

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?

Names the alternative (taifoon_hire) and its selecting condition, and explains the no-payment flow (returns payment terms) so the agent knows the two-step pattern. It does not rule out other siblings such as taifoon_find or taifoon_grade, which would make routing fully unambiguous.

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