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

Beyond the readOnlyHint annotation, the description discloses return behavior: 'Returns dated matches with source context; source_file and snapshot_digest may be null for the multi-source result.' This adds meaningful expectations about the output format and potential null fields, which is valuable for an agent.

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, each serving a distinct purpose: what it does, what it returns, and when to use it. No fluff, front-loaded with the action, and appropriately concise.

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 single-parameter search tool with no output schema, the description fully covers the purpose, usage scenarios, and return behavior. It provides enough context for an agent to decide when and how to invoke the tool without needing supplemental documentation.

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 input schema already thoroughly describes the only parameter ('name') with the same source context. The description adds no additional parameter-level detail, so the schema coverage baseline of 3 applies.

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 ('Search') and clearly identifies the resource (sanctions and watchlist data) with explicit sources (OFAC, EU, UK, UN, plus Fonteum named exclusions). It goes beyond a generic phrase and is well-positioned to be distinguished from siblings, even though it doesn't explicitly compare to them.

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 explicitly states when to use the tool: 'Use for sanctions screening, entity due diligence, or any “is this entity sanctioned?” question.' This provides clear context, but it doesn't mention when not to use it or offer alternatives, so it falls short of a 5.

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