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

Annotations already indicate read-only and idempotent behavior, and the description adds important non-obvious context: it costs $0.10 USDC, it does not verify bank-account ownership or sanctions, and it returns deterministic reason codes. This meaningfully exceeds what the annotations alone convey.

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 compact and front-loaded with the most important guidance: when to use it. Every sentence adds distinct value—timing, process, output, cost, limitations, and the free-preview alternative—with no redundant filler.

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 paid, decision-returning API with no output schema, the description provides the essential invocation context: cost, when to use, what it returns, what it cannot do, and which sibling to try first. The extensive input schema covers parameter details, so nothing critical is missing.

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 92%, so the schema already documents the parameters well. The description contributes only high-level grouping, such as 'invoice identity and contact domains' and 'payment-change and urgency signals,' which adds context but does not materially improve per-parameter understanding beyond the schema.

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 names a specific verb and resource: it assesses an Israeli vendor before payment and returns a PROCEED, REVIEW, or BLOCK decision. It clearly separates itself from the free preview sibling by stating 'Use preview_israeli_vendor_payment_risk_free first,' so an agent can select the correct tool without opening schemas.

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 states exactly when to use the tool: immediately before paying an Israeli supplier. It also names the free preview as the prerequisite alternative and lists capability exclusions, telling agents when this tool is insufficient.

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