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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral clarity by emphasizing this is a dry-run that never signs or submits a payment and does not claim legal wallet ownership. This goes beyond annotations and clarifies a critical distinction for an agent considering payment actions.

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 a single informative sentence, front-loaded with the key purpose ('FREE AGENT PAYMENT FIREWALL') and a clear before-signing gate. It includes a defensive clarity sentence about not signing/submitting. It is compact and each sentence earns its place, though the all-caps acronym could be seen as stylistic noise.

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?

Given the output schema exists and annotations cover safety, the description captures the essential behavioral promise: free dry-run, decision verdict, and no signing/submission. The complexity of the nested inputs is high, but the schema itself is rich. The description doesn't mention return value shape or result handling, but the output schema likely covers that; a brief mention of ALLOW/REVIEW/DENY actually covers the output concept.

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 could compensate, but it does not explain any parameters individually. It does enumerate the conceptual input categories (Israeli company identity, service origin, signed domain payee manifest, destination wallet, payment fingerprint, buyer mandate) which loosely map to schema properties. However, with 9 parameters and nested object structures, the agent must rely entirely on the schema for actual parameter meaning.

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 clearly states the tool performs a dry-run preview of an x402 payment trust decision, binding multiple inputs into an ALLOW/REVIEW/DENY verdict. It distinguishes itself from signing/submitting via the 'never signs or submits' clause. However, it does not explicitly differentiate itself from the several similarly-named preview 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?

The description conveys when to use this tool: before signing an x402 payment, to get a free firewall/decision. It also states what it does NOT do (never signs or submits), providing an implicit exclusion from signing tools. It doesn't explicitly name alternatives like preview_israeli_invoice_payment_gate_free or when not to use it, but the x402-specific scope is clear.

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