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

Annotations already declare readOnly/idempotent/openWorld, and the description adds substantive context beyond them: OFAC SDN carries ~500 digital-currency addresses, UN designations surface through the EU/UK entries with UN numbers, and results include each list's date and SHA-256 (provenance/versioning). It does not disclose how matching is scored, what the threshold does, or how many hits are returned by default.

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 sentences, front-loaded with the question the tool answers, followed by list scope and output provenance. Dense but every clause carries selection-relevant information; the '~500 digital-currency addresses' parenthetical is slightly incidental but supports choosing this tool for wallet screening.

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 some work describing hit shape (UN number, list date, SHA-256). But for a 6-parameter tool with a required-either/or input, an undocumented match threshold and unpaginated-hit behavior leave meaningful ambiguity about how results are produced and bounded.

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 50%; name, address, and lists are documented in-schema, and the description's note that UN entries arrive via EU/UK with a UN number usefully reinforces the `lists` semantics. However `threshold` (a fuzzy-match cutoff defaulting to 0.85), `limit`, and `kind` get no explanation anywhere, so the description does not compensate for the gap.

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?

Opens with a concrete question ('Is this wallet address or name on a public sanctions list?') naming the resource and both accepted identifier types, then enumerates the exact lists covered. None of the siblings (company_lookup, eori_check, lei_lookup, vat_check) do sanctions screening, so the boundary is unambiguous.

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 closing clause 'A lookup, not a compliance determination' scopes usage and warns against over-reading results, which is real guidance. It stops short of naming alternatives or stating prerequisites (e.g., which identifier to prefer when both are available), so it is clear but not exhaustive.

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