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

Annotations are sparse (readOnlyHint false, openWorldHint true, idempotentHint false, destructiveHint false), so the description carries the burden of behavioral disclosure. It transparently discloses that the tool is paid, the exact cost (0.01 USDC via x402 on Base), the two-step flow (call without payment to receive MCP PaymentRequired, then retry with payment), and the legacy parameter alternative. It also clarifies it is a point-in-time scan, not a readiness check. This goes well beyond the annotations and gives the agent essential operational detail. It does not, however, mention any rate limits or concurrency behavior, which is a minor gap given the context.

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 long but densely packed with necessary operational details: purpose, usage order, payment mechanism, two-step flow, and legacy support. It front-loads the primary purpose and usage, then dives into payment specifics. While it could be trimmed slightly, every sentence carries critical information for a paid tool with a nontrivial flow. It is not bloated; the length is justified by the 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?

For a paid, two-step tool, the description covers the essential call sequence (without payment → PaymentRequired → with payment) and the legacy path. It also specifies the payment amount, token, and network. It does not describe the report content, but an output schema exists (per context signals), so that is handled. It also omits any mention of rate limits or idempotency, but annotations already flag idempotentHint false. Overall, the description is complete enough for an agent to successfully invoke the tool, with minor gaps that are unlikely to cause errors.

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%, so the schema already explains all three parameters. The description adds minimal new parameter-level meaning: it repeats the target_url description, mentions the _x402_payment parameter's role in the two-step flow, and references agent_id as optional. The payment flow context is useful but is more about overall behavior than parameter semantics. Per the rubric, when schema coverage is high, the baseline is 3, and the description does not substantially enhance parameter understanding beyond what the schema provides.

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 opens with a clear, specific purpose: 'structured trust report for a public agent card or A2A endpoint before routing money or user work to it.' It also distinguishes itself from siblings by stating it is 'a paid point-in-time scan, not an endpoint-readiness check,' and references the free alternatives (can-pay, readiness checks). This leaves no ambiguity about what the tool does and how it differs from nearby tools.

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 gives explicit when-to-use guidance: 'Use when an agent needs a structured trust report... before routing money or user work to it.' It also prescribes a usage order: 'run free can-pay and readiness checks first; pay only when policy allows,' and explains the two-step payment flow. This is comprehensive and actionable, clearly steering the agent toward the correct workflow and away from premature payment.

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