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

The description goes beyond annotations by disclosing cost ($0.01 USDC per call), the limitation that inflow is not proven to be x402 sales revenue, and the scanned_days caveat for trend windows. These are important behavioral traits not captured by the readOnlyHint, idempotentHint, or destructiveHint. No contradiction with annotations.

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 efficiently structured: it starts with purpose, then usage, caveats, and cost. Each sentence earns its place and provides distinct value without redundancy. The length is appropriate for the tool's complexity.

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?

Given no output schema, the description sufficiently conveys the return signals, including the scanned_days field and per-window flags. It also covers limitations and cost, making it complete for an agent to invoke and interpret the result.

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 input schema fully describes the only parameter with format and examples, so baseline is 3. The description adds little about the parameter itself beyond 'one listing,' which does not materially improve on the schema.

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 it observes on-chain revenue signals for one listing and lists specific metrics (USDC inflow, payers, modal transfer size, trends, percentile), distinguishing it from sibling tools like credit score or wallet authenticity. The verb 'estimate' and resource 'endpoint revenue' are explicit.

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 a clear use case: 'Use this to size a seller's real traction.' It does not explicitly name alternatives or exclusions, but the unique focus on revenue signals differentiates it from siblings. The caveats about data interpretation also guide when to trust the result.

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