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

Annotations already establish this as a safe, closed-world read (readOnlyHint=true, openWorldHint=false). The description contributes real context beyond them: the cost gate of 5 prepaid credits and the production-billing requirement, which affects whether an agent should call it at all. It stops short of describing how ties are broken or what the ranking output contains.

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 short sentences, front-loaded with the operation and followed by the critical billing constraint. Nothing is padded, though the capitalized 'PAID ONLY' reads as a banner rather than integrated guidance.

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 one-parameter, read-only ranking tool, the definition covers the operation and the gating cost. With no output schema present, the missing piece is a brief indication of what the ranking returns (order, per-vendor scores), which keeps it from a 5.

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?

There is a single parameter at 0% schema description coverage, so the schema alone conveys almost nothing about the expected array element shape. The description partially compensates by naming the three score dimensions (cost, security, reliability) each vendor entry should carry, but it never states the field names or types, leaving the actual payload format to guesswork.

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 (rank) plus the resource (candidate vendors) and the inputs it consumes (cost, security, reliability scores). It does not explicitly contrast with the nearby privi_pro_vendor_risk sibling, so an agent must infer the boundary, but the operation itself is unambiguous.

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 only usage-relevant guidance is a billing precondition ('PAID ONLY: 5 prepaid credits'). There is no statement of when to pick this over privi_pro_vendor_risk or other vendor tools, and no exclusion criteria for what counts as a candidate vendor.

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