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

Annotations already cover safety (readOnly, idempotent, non-destructive), so the description's contribution is the important caveat that results are derived by filtering a cached snapshot on listedOn rather than a true delta feed, which tells the agent the data provenance and accuracy limits. It omits return shape, ordering, and how limit interacts with the snapshot, keeping it shy of 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 sentences, front-loaded with the core action and scope, followed by a single justification clause about data provenance. No waste, no restating the name.

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 read-only filtered-list tool with full schema coverage and no output schema, the description supplies the essential behavioral caveat (snapshot-derived delta) an agent needs to interpret results correctly. Minor gap: no hint about what an entity record contains or whether the result includes both added and updated uniformly.

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 baseline is 3, but the description adds real meaning beyond the schema: it clarifies that 'since' is compared against the listedOn field and that source selects among four official lists. The limit parameter's interaction with the snapshot is not elaborated, so not a 5.

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 (return entities added or updated), a temporal scope (since a given ISO date), and a constrained resource (a chosen source list from four official lists). An agent can immediately distinguish this delta/change-feed tool from sibling point lookups like sanctions_screen_entity or sanctions_search_alias.

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?

Implies the use case clearly: retrieve a delta since a date rather than screen or look up a specific entity. The caveat about non-uniform public delta feeds explains why the tool works as it does, though it never explicitly names a sibling to use instead (e.g., for full-snapshot retrieval).

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