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

Annotations already cover read-only, idempotent, open-world and non-destructive semantics, but the description adds materially new behavioral facts: the $0.05 per-call x402 pricing on Base, the prepaid x-credit-token header for unlimited calls, no free tier, and no API key requirement. These are things an agent cannot infer from annotations or schema.

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-loaded with the decision question and the scoping claim, then the payload contents, verdict taxonomy, and payment terms in descending priority. It is somewhat verbose with rhetorical framing and em-dash asides, but nearly every sentence conveys information an agent needs.

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, return-value detail is unnecessary, and annotations cover the safety profile. The description still supplies the verdict enum, the audited dimensions, the payment/access requirements, and the protocol uniqueness claim, leaving nothing an agent needs in order to call it correctly.

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?

There is a single required parameter with 100% schema description coverage, so the schema already carries the semantics. The description only restates that 'operator' is required and does not add format guidance (e.g., address normalization), so the baseline of 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?

States a specific verb and resource (audit a Commerce Payments operator), explains what the operator does, and enumerates the concrete outputs: 90-day volumes, fees taken, capture-vs-reclaim record, distinct payers and merchants. It also distinguishes itself from siblings by noting no other tool reads this new Base commerce protocol.

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?

Frames the use case explicitly — run this before relying on an operator to authorize escrow or capture for merchants — which tells the agent when the tool applies. It does not name a competing tool or state exclusions, but the claim that no sibling reads this protocol effectively removes ambiguity about alternatives.

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