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

Annotations cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), and the description adds valuable non-obvious context: the exact price (0.005 USDC), the network (Base Mainnet), the x402 v2 protocol, the payment meta-key required for retry, and the payment-response meta returned after settlement. It does not cover failure/refund behavior when settlement fails, which keeps it from a 5.

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?

Three sentences, front-loaded with the value proposition before the payment mechanics. Dense but every sentence carries distinct information (what it returns, no account needed, how to pay/retry). Minor use of protocol jargon that could be tightened.

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 no output schema, the description fills the gap by naming the return payload (1+ verified counterparty with public evidence, compact decision summary, payment-response meta). For a two-parameter read tool with full annotation coverage, this is close to complete; the only missing piece is error/refund handling.

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 both parameters (q, journeyId) are already documented in the schema. The description adds no format, length, or example detail beyond the schema baseline, so the standard 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+resource: 'one-call paid procurement evidence' for supplier sourcing, vendor discovery, and counterparty research. This is clearly distinguishable from the free-preview and commerce-quote siblings by the 'paid evidence' framing, though no sibling is named explicitly.

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 walks through the x402 invocation sequence (first call returns PaymentRequired, retry the SAME call with payment), which is genuinely useful procedural guidance. However, it never states when to prefer this paid offer over siblings like mars_free_commercial_intelligence_preview or discover_commercial_counterparties, leaving the routing decision implicit.

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