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

With no annotations, the description carries the full burden and does well: it discloses the paid x402 mechanism, exact price, and network (eip155:8453), the covered chain families, and the boolean-plus-entity return. It stops short of error behavior for malformed addresses or list-freshness guarantees, which keeps it below 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?

Two compact sentences with the cost/transport tag front-loaded, then purpose, coverage, and return value. Nothing is redundant and everything is front-loaded for fast scanning.

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 single-parameter lookup with no output schema or annotations, the description covers cost, transport, coverage, and return semantics adequately. It could add one line on invalid-address behavior or how current the OFAC list is, but an agent can call it correctly as written.

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% and only one parameter exists, so the baseline is 3. The description nonetheless adds real meaning: it enumerates the accepted chain families (BTC, ETH/EVM, TRON, LTC, XMR, SOL) that constrain what a valid address string looks like, going beyond the schema's generic '0x… or bc1…' example.

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 (check) and resource (crypto address) plus the exact data source (OFAC SDN digital currency addresses) and the return shape. It is clearly a single-address sanctions lookup, distinguishable from the sibling sanctions_screen by virtue of operating on addresses rather than names/entities.

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 implies when it applies (a crypto address needs sanctions screening) but never says when to prefer it over the sibling sanctions_screen or what to do when the chain is unsupported. The paid-per-call note is useful gating context but not a usage rule.

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