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

The description discloses a non-obvious behavioral trait: because not all official lists expose a public delta feed, results are derived by filtering the cached snapshot by listedOn. This adds real context beyond the readOnlyHint and idempotentHint annotations and helps the agent understand possible data limitations.

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 with no filler. The operation is front-loaded, and the second sentence earns its place by explaining an important implementation caveat.

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 relatively simple read-only delta query, the description plus schema covers the key details: since, source, and the cached-snapshot behavior. It is slightly incomplete because there is no output schema and the description does not describe response shape or pagination behavior, leaving some inference to the agent.

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?

The schema already documents since and limit reasonably well, and source is constrained by an enum. The description adds some context by calling the sources the 'four official lists,' but it does not clarify limit behavior or explain the source enum values beyond that. Overall the description provides only modest extra parameter meaning.

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 description uses a specific verb and resource: returning entities added or updated since an ISO date for a selected source list. This clearly distinguishes it from sibling sanctions tools like sanctions_get_entity or sanctions_screen_entity, which fetch or screen rather than compute deltas.

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 clearly frames the intended use case: get a delta of entities added or updated since a date for one of four official lists. It does not explicitly name alternatives or exclusions, but the cache caveat gives useful context about feasibility and behavior.

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