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

The annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds valuable behavioral context beyond those: it is a paid resource with an explicit x402 price, and it is positioned as appropriate for selection routing where the result is unverifiable. This helps the agent understand cost and reliability implications without contradicting the 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 three sentences with no filler. The core behavior is front-loaded, followed by scope clarification, prohibitions, and cost information. Every sentence adds distinct value for tool selection and invocation.

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 tool with nested parameters, no output schema, and no parameter descriptions, the description covers the key invocation concerns: what is ranked, what inputs influence ranking, which domains are off-limits, and the cost. It could be more complete by describing the return shape or ranked result format, but 'Ranks...' sufficiently implies the output for most routing purposes.

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 0%, so the description must carry semantic weight. It does this by naming the ranking dimensions (price, reliability, latency, trust, quality) and explicitly mentioning 'caller-supplied constraints and weights,' which maps to the constraints and weights objects in the schema. It does not explain every nested field, but the schema's property names are largely self-explanatory and the description supplies the missing 'what the tool does with them' semantics.

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 specific verb and resource: 'Ranks caller-supplied candidates' using explicit signals, constraints, and weights. It also differentiates its role with 'Intended for selection routing / result unverifiable' and explicitly excludes legal, identity, sanctions, fraud, contractual, and regulatory adjudication, making it distinguishable from verification and policy-engine siblings.

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?

It states when to use the tool ('Intended for selection routing / result unverifiable') and provides a strong when-not list ('Do not use for legal, identity, sanctions, fraud, contractual, or regulatory adjudication'). It does not name an alternative tool for those prohibited cases, so it stops short of full alternative routing.

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