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

Annotations cover the safety profile (readOnly, idempotent, non-destructive, closed world), and the description goes well beyond them with access and quota facts an agent needs: free, no account, 200 lookups per day per internet address. It also discloses result truncation (up to 5 aliases, 3 locations), warning that the record may be partial.

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 what is returned before the operational constraints. Every clause carries distinct information: identity, field inventory, truncation caps, and quota.

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?

An output schema exists, so return values need no prose, yet the description flags the aliases/locations caps that the schema alone would not surface. Combined with the auth and rate-limit context, an agent has everything needed to call this correctly and plan around the quota.

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?

One parameter at 100% schema coverage, so the baseline is 3. The description restates the schema's own wording ('the id a search result gave' vs 'The id of a search result') without adding format, casing, or sourcing detail beyond it.

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 retrieval action and resource: one sanctions list entry, fetched by the id a search result returned, with the exact fields it carries. This separates it from search (which produces the id) and from the screening siblings, though the differentiation from screen_entity/screen_address is implied rather than stated and the bare name 'fetch' adds nothing.

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?

'by the id a search result gave' establishes the precondition clearly: this is a follow-up to a search, not a discovery tool. It gives no explicit exclusions (e.g. when to prefer screen_entity instead), so it lands short of a full when/when-not statement.

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