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

Beyond the readOnlyHint/openWorldHint annotations it discloses the matching mode (exact, not fuzzy), case-normalization behavior per encoding, a source-cache staleness window of up to one hour, and the epistemic limit that a non-match is not clearance. It also states the paid-call cost and the exact failure behavior (returns x402 payment requirements) so the agent can recover without guessing.

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?

Six short clauses, front-loaded with the matching semantics before cost and payment mechanics. The telegraphic style carries no filler; each sentence introduces a distinct fact (scope, normalization, cache, caveat, price, retry path).

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?

With no output schema, the description does explain the unpaid response shape but never describes what a successful match result contains (e.g., whether SDN entry identifiers or just booleans are returned). For a single-parameter screening tool this is a minor gap rather than a blocking one.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning the schema lacks: EVM hex addresses are case normalized while other encodings are case sensitive, which directly affects how the agent should format inputs. It also clarifies that identity fields are intentionally absent from the request.

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 first sentence gives a specific verb and resource ('Exact crypto-address matching against the official OFAC SDN XML') plus a hard scope limit ('up to 50 addresses') and an explicit exclusion ('No identity data'). An agent can tell this is a sanctions-list address screener rather than a general compliance tool without consulting the 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?

It sets clear interpretive boundaries — 'Non-match is not sanctions clearance' — and spells out the procedural path when payment is missing (retry with X-PAYMENT, PAYMENT-SIGNATURE, or params._meta['x402/payment']). It does not route the agent toward or away from any sibling such as trade_compliance_pack, so alternative selection is left implicit.

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