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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered; the description adds genuinely non-structural behavior: only matches consume a query ('Solo los match gastan consulta') and the Pro plan requirement. It stops short of explaining how to act on an 'ambiguous' result beyond the province parameter's own schema note.

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?

Four short sentences, front-loaded with the core transformation, then result states, use case, cost, alternative and plan. Every sentence carries distinct information with no repetition.

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?

There is no output schema, and the description compensates by enumerating the three possible per-item outcomes plus the billing rule. Minor gaps remain: result ordering/alignment with the input array and behavior at the 100-item boundary are not addressed, but nothing critical to invoking it 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%, so both parameters (names, province) are already documented in structured form and the description need not compensate. The description restates the 100-item cap already encoded in maxItems but adds no new meaning about the province disambiguation semantics. 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 and resource — converting a LIST of company names (up to 100) into CIFs — and defines the per-item outcome vocabulary (match, ambiguous, no_match). It also explicitly contrasts itself with the single-name sibling search_companies, so the tool is distinguishable without opening any 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?

Gives a concrete use case (filling in client/supplier sheets that only have a name) and an explicit alternative with its selecting condition: 'Para un solo nombre, search_companies.' It also states a prerequisite, 'Plan Pro', which an agent needs before committing to the call.

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