company_by_nif

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

No annotations provided, so description must convey behavior. It adequately explains that the tool relies on cross-referenced open sources and covers only a subset (~232k companies). It does not mention authentication or rate limits but is transparent about lookups being non-destructive and the meaning of missing results.

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 concise and well-structured, with a clear first sentence stating purpose, followed by context and recommendations. Every sentence adds value without redundancy.

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 presence of an output schema, the description adequately covers the tool's functionality, limitations, and suggested follow-up. It provides sufficient context for an agent to use the tool correctly.

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?

Input schema has 0% description coverage for the single parameter 'nif'. The description adds meaning by explaining it's a tax ID and tying it to the tool's purpose, but does not specify format or validation rules. Partial compensation for lack of schema descriptions.

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 purpose: 'Look up a Spanish company by its NIF/CIF tax ID.' It provides specific context about the data source (BORME cross-referencing) and distinguishes itself from siblings like recent_signals and list_act_types by being a lookup tool.

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?

Explicit guidance on when to use and limitations: 'A miss means not matched yet, not does not exist.' It also recommends follow-up with company_history using the returned slug on a hit, providing a clear workflow.

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