Search a national company register by name

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, and the description adds substantial behavioral detail beyond them: search hits are deliberately thin, order is the register's own relevance order, zero hits returns an empty array and hint, and errors have a structured shape with retry guidance. It also notes that 'UK' is rejected and country codes should not be hard-coded, reinforcing the openWorldHint.

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 long but every sentence carries operational value. It is front-loaded with the core purpose and usage, then moves into edge cases and error handling in a logical order. No filler or tautological repetition; the length is justified by the tool's complexity.

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?

The description is complete for a search tool of this complexity. It covers return-value expectations (thin hits, confidence, relevance order), zero-hit semantics, error codes and retry policy, supported countries, and how to proceed to `lookup_company`. The presence of an output schema makes it unnecessary to document every return field, and the description still adds useful context about interpretation.

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?

Even though schema coverage is 100%, the description adds meaning beyond the schema: it explains what each country code maps to, why `name` is free text rather than an identifier, the exact bounds and failure behavior for `limit`, and the presence of a `confidence` field on hits. This significantly improves the agent's ability to use the parameters correctly.

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 verb, resource, and scope: "Search a national company register by name, when you have a name rather than an identifier." It explicitly contrasts with `lookup_company`, which is the sibling it must not be confused with, and explains the two supported country-specific registers.

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 gives explicit when-to-use guidance: use it when the user provides a company name, then call `lookup_company` with the `id` of the right hit. It also covers when NOT to treat zero hits as an error, how to handle invalid input, and when to call `list_countries` first, leaving no ambiguity about tool routing.

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