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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: no API key required, and results are a masked free preview of search_entities, which implies a limited result set. It could go further on preview limits (result caps) but the key traits are disclosed.

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?

Front-loaded with the highest-signal fact (free, no API key) and compact at four short sentences. There is minor redundancy in restating the id-to-fetch handoff twice.

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?

Covers trigger, cost/auth prerequisite, geographic scope, relation to siblings search_entities and fetch, and the return shape, even though an output schema already exists. Nothing an agent needs to call it and chain onward is missing.

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% and the single query parameter already carries a constraint and example ('inmobiliaria Valencia'). The description only implies the parameter's content ('find companies or businesses'), adding no syntax or format detail beyond the schema, so the 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?

States a specific verb and resource: 'Search the ENTIA business registry (Spain first; also EU)'. It also positions itself against siblings by noting it 'wraps search_entities with the free preview mask' and that returned ids are passed to fetch, so the agent can distinguish it from search_entities and fetch without opening schemas.

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?

Gives an explicit trigger ('Use when the user asks to find companies or businesses') and names the downstream tool ('pass an id to fetch'), which makes the search-then-fetch workflow clear. It stops short of stating when to prefer the full search_entities instead, leaving the promotion path to inference, though the 'FREE (no API key needed)' framing hints at the selection criterion.

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