Look up company by national ID

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

With no annotations provided, the description carries the behavioral disclosure burden and does so well: it reveals country-aware routing, support for multiple national ID formats, and a defined return type ('single company object with core identity, address, legal form, status flags'). It doesn't cover error/edge behavior, but the core behavior is transparent.

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?

Two sentences, front-loaded with the main purpose, and every clause adds functional value—alternatives, shapes handled, and return contents. No filler or 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?

Despite no output schema, the description specifies what the returned object contains and covers the main complexity (different national ID shapes and country disambiguation). For a lookup tool, this is complete enough for an agent to confidently invoke it.

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 the schema already fully documents both parameters including format examples and the SK↔CZ collision issue. The description adds context about 'all our shapes' but largely repeats schema content. The baseline of 3 applies because the description doesn't significantly augment the schema.

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 opens with a specific action—'Resolve a single company by its national registry identifier'—and explicitly scopes the tool to country-disambiguated lookups by national ID. It also differentiates from sibling tools by contrasting with search_companies for name-based discovery.

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?

It explicitly states when to use the tool: 'Use this when you already know the registry number'. It also gives an alternative: 'use search_companies for name-based discovery', which clearly directs the agent to the right sibling.

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