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

Goes well beyond the readOnly/idempotent/openWorld annotations: it discloses the 90-day lookback, the Base-USDC-only scope, the crucial interpretive caveat that absence reads as 'thin' and never as bad, and the commercial mechanics ($0.03 per call over x402, prepaid x-credit-token header for unlimited calls, 1 free call/day, no API key). Those are material facts an agent cannot infer from structured fields.

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?

Front-loads the decision question and the observed signal pattern before the mechanics, which is the right ordering. It is dense but nearly every sentence carries an interpretive or operational fact; the 'Not financial advice' clause is minor filler, keeping it just short of 5.

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?

With an output schema present, the description need not explain return shape; instead it supplies what the schema cannot: coverage limits (Base USDC only), the time window, how to read a null result, and the payment/auth model. Nothing an agent needs to call it correctly is missing.

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 description coverage is 100% and there is a single parameter, so the schema already documents 'wallet'. The description only restates 'Required input: wallet' without adding format, address-vs-ENS, or chain semantics, so the baseline 3 applies.

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?

Opens with a specific decision question (real repeat customer vs one-shot sampler) and then states exactly what it reads: a wallet's outgoing USDC payments on Base over 90 days, computing breadth, depth, and repeat-payee signals. It explicitly distinguishes itself from its sibling by naming 'the payer-trust mirror of x402-seller-check', so an agent can route without opening either 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?

Clear context is given for when to reach for it (assessing whether a payer is a genuine repeat customer) and the alternative framing versus x402-seller-check is named. It stops short of explicit when-not conditions or named substitutes for the non-x402 case, so it is strong but not exhaustive.

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