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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds useful context beyond that: the breadth of identifier shapes handled and the shape of the returned core record (identity, address, legal form, status, NACE). It does not disclose what happens on no-match or on the country tie-break beyond what the schema says.

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?

Three sentences, zero filler: identity/scope first, then capability breadth, then return payload, then routing to alternatives. Every clause earns its place and the routing information is front-loaded.

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?

For a 3-parameter lookup with an output schema, full schema coverage, and a complete annotation set, nothing needed to call it correctly is missing. The description only needs to carry routing and identifier-shape context, which it does.

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 baseline is 3, but the description adds identifier-shape examples ('AT Firmenbuch e.g. "187a"', SI/LV registry numbers) that broaden the schema's own example list and reinforce the single-resolution constraint tied to 'ico' and 'country'. The 'purpose' enum semantics remain schema-only, so it is not a full 5.

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+resource+scope: 'Resolve exactly one company by its national registry identifier in a given country.' It also distinguishes itself from two named siblings (company_brief, get_company_details), so an agent can route 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?

Explicitly names the two alternatives and the condition that selects each: company_brief for an LLM-ready summary, get_company_details for the full enrichment layer. The 'exactly one' framing also implicitly excludes bulk/search use cases covered by search_companies and advanced_search.

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