Look up a director by DIN

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds useful behavioral context: the explicit scope exclusion 'No personal contacts' and the workflow instruction 'Cite source_url', both of which are not in the structured fields.

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?

One dense sentence plus two short fragments, front-loaded with identity and keyed parameter, and the scope limitation is stated last without padding. Every clause carries information.

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, the description usefully enumerates the returned fields (status, disqualification, board memberships) and the citation behavior, which is what an agent needs to interpret results. It stops short of describing result shape or what happens when a DIN is not found.

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 description coverage is 100% with a single parameter, so the schema already documents 'din' as an 8-digit DIN with min/max length 8. The description restates the 8-digit format but adds no syntax, validation, or sourcing detail beyond it, so baseline 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?

States a specific verb (look up) and resource (one director) keyed by an 8-digit DIN, and enumerates what the record contains: DIN status, disqualification, and board memberships. This clearly separates it from lookup_company and search_companies without needing the schema.

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 'one director by 8-digit DIN' framing implies a single-record, ID-keyed lookup as opposed to a search, so usage is inferable. However, it never explicitly says when to use this versus lookup_company or what to do if the DIN is unknown, so no exclusion or routing guidance is given.

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