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

The description carries real behavioral weight beyond the annotations: a concrete price ($0.02/call), the settlement rail (USDC on Solana via x402), the exact retry protocol (_meta["x402/payment"]), and an HTTP fallback URL. The payment flow also explains why readOnlyHint is false despite the read-like nature of the call. It omits error/not-found behavior, 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?

Two sentences, front-loaded with the operation and followed by the payment/pricing detail that an agent must know before calling. The parenthetical is dense but every clause is load-bearing; only the HTTP URL is arguably optional.

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 is the only source of return-value information, yet "full normalized recall record" is undefined — the agent cannot tell what fields come back. Pricing and transport are complete; the response shape and not-found behavior are not.

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 coverage is 100% and the id property already documents the source-prefixed format with three concrete examples, so the description adds nothing further about the single parameter. Baseline 3 applies when the schema does the work.

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?

"Fetch one full normalized recall record by its id" gives a specific verb (fetch), a specific cardinality (one), and a resource (recall record), which cleanly separates it from recalls_search and recalls_vehicle. It stops short of naming a sibling outright, so it lands at 4 rather than 5.

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?

Usage is only implied: the id-format examples in the schema signal "use this when you already have a source-prefixed id," but the description never states when to prefer this over recalls_search or recalls_product_check, and gives no exclusions or prerequisites beyond payment.

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