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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior, so the bar is lower. The description adds genuinely non-obvious operational facts: a 0.005 USD cost via x402 and a signed receipt in the response — payment requirements are exactly the kind of context annotations cannot convey. Rate limits and failure modes are not covered, so not a 5.

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?

Three dense sentences, front-loaded with what is screened and against which list, then usage, then return shape and cost. No filler, and the cost/payment note is placed where an agent will read it before calling.

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 lookup with an output schema, the description covers everything an agent needs to decide and call: data source, supported chains, trigger condition, return contents, price, and payment mechanism. Return-value details are correctly summarized rather than restated.

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?

With a single parameter at 100% schema coverage, the schema already documents `address` fully, so baseline 3 applies. The description's chain enumeration (EVM, BTC, TRX, SOL, USDT, USDC) largely restates the schema's own example list, adding only marginal information.

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+resource: sanctions screening of a crypto address against the US OFAC SDN list, with the exact address families covered. It is unmistakably distinct from siblings like check_ai_consent or can_ai_use, which concern AI consent rather than wallet sanctions.

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?

"Use it before an agent pays, receives from or interacts with a wallet" gives a concrete triggering context for invocation. It stops short of naming an alternative tool or stating when not to use it, but the scope boundary ("Screening aid, not legal advice") clarifies the limits of the answer.

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