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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the description is free to spend its words on what those hints cannot convey: list provenance (per-list date and SHA-256), that OFAC SDN carries ~500 digital-currency addresses, that UN designations surface through UK/EU entries with UN numbers. It omits matching behavior (how the threshold decides a hit) and any latency/rate context.

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 sentences, front-loaded with the core question, then dense factual qualifiers, then the scope caveat. Every clause carries information and nothing is repeated from the schema or annotations.

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 and 50% schema coverage, the description should carry more of the result-interpretation burden. It handles source provenance well but leaves the scoring model (threshold) and result caps (limit) unexplained, which matters for an agent deciding whether a returned hit is meaningful.

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% and the description reinforces the two well-documented inputs (address, name) plus the lists enum and its UN semantics. It says nothing about the three undocumented parameters — kind, limit, and especially threshold (0.7–1.0), whose fuzzy-match meaning is the most consequential unknown for interpreting hits.

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 direct question-form verb+resource ('Is this wallet address or name on a public sanctions list?') and enumerates the exact data sources (OFAC SDN, EU, UK, UN). That scope is enough to separate it from every sibling, all of which are corporate/registry lookups (company_lookup, lei_lookup, eori_check, vat_check) rather than sanctions screening.

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' explicitly bounds when the output is appropriate to rely on, which is unusually useful guidance for this tool class. It does not, however, name any alternative or a when-not-to-call condition beyond that scope caveat.

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