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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely new behavioral context the annotations cannot convey: the $0.05 per-call cost from the API key balance and the free tier of 3 screens per day without a key — pricing an agent can reason about before invoking.

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, zero waste. The core capability is front-loaded, and the comparison, limitation, and pricing follow in priority order — each clause earns its place.

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 three nested parameter groups and no output schema, the description covers purpose, sibling routing, and cost, but never describes what the screen returns (a hit/no-hit result, match scores, list references). With no output schema to fall back on, that is a meaningful gap for an agent deciding how to consume the response.

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 only 33% and the schema is deeply nested, so the description carries more burden than usual. It clarifies that the payee name is the core input and the crypto wallet is optional, but says nothing about the context or payment sub-objects, whose many fields drive results ('Each field sharpens fraud detection').

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 (screen) and resource (payee name plus optional crypto wallet) against named targets (OFAC sanctions lists and embargoed jurisdictions). It also explicitly contrasts itself with the sibling check_counterparty, so an agent can distinguish the two without opening either schema.

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?

Names the alternative (check_counterparty) and gives the tradeoff — faster and cheaper, but no fraud-pattern detection — which effectively tells the agent when to pick this tool versus the broader one. It stops short of an explicit 'use this when X, not when Y' statement or stating prerequisites for the inputs.

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