cvr_lookup

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

With no annotations, the description carries the full burden of disclosing behavior. It states 'Returns full company details,' which indicates the nature of the output, but it does not disclose potential error behavior (e.g., what happens if the CVR number is not found), whether the operation is read-only, or that the `country` parameter can return Norwegian data. The description provides only a minimal behavioral snapshot.

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?

The description is a single sentence of 15 words, front-loaded with the verb 'Look up' and the resource. It contains no filler and every word serves a purpose. This is 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?

Given the tool's low complexity (2 params, no output schema), the description is adequate but has gaps. It does not explain what 'full company details' includes, nor does it mention the `country` parameter or provide guidance on using `cvr_search` as an alternative. Since there is no output schema, the description should provide more detail about the return value and potential edge cases.

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%, so the baseline is 3. The description itself adds no extra meaning to the parameters; it only mentions '8-digit CVR number,' which is already in the schema's description. It does not clarify the `country` parameter's role, and the description's focus on 'Danish' could even conflict with the country enum. Thus the description adds no value beyond the schema.

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 clearly states the tool's function: 'Look up a specific Danish company by its 8-digit CVR number. Returns full company details.' It uses a specific verb and resource, and distinguishes from the sibling `cvr_search` by focusing on exact-number lookup. However, the description is slightly misleading because the schema allows a `country` parameter with values 'dk' or 'no', yet the description only mentions Danish companies, which conflicts with that broader scope.

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 implies when to use this tool: when you have a specific 8-digit CVR number. It says 'Look up a specific... by its 8-digit CVR number,' which gives clear context for when to use this tool over a search tool. However, it does not explicitly mention the sibling `cvr_search` or explain when to prefer one over the other, so it lacks explicit exclusion/alternative guidance.

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