ch_validate_uid

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

Annotations already mark the tool as read-only and open-world, and the description adds meaningful behavioral detail: it performs a local check-digit verification first, then optionally performs a network lookup to the UID register, returning status and VAT-registration information. This clearly discloses the two-step behavior and the network call without contradicting the annotations.

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?

A single, well-constructed sentence front-loads the verb and object, then efficiently describes the check flow, the default behavior, and the optional lookup=false switch. There is no filler, repetition of schema details, or unnecessary background.

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 tool with two parameters, read-only annotations, and no output schema, the description covers the input type, the default network lookup, and the key result dimensions (register recognition, status, VAT registration). It does not specify the exact response fields or error behavior, but those are not strictly necessary for an agent to decide whether to invoke this tool.

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?

The input schema already fully documents both parameters, including format examples and the lookup default. The description adds some value by associating lookup with the local-check vs register-lookup sequence, but it does not introduce substantive parameter semantics beyond what the schema already provides.

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 uses a specific verb ('Check') and a clear resource ('a Swiss UID or VAT number'), then breaks down exactly what checking involves: local checksum validation and optional UID-register lookup. It is immediately distinguishable from sibling tools like ch_company_search or ch_company_profile, which focus on company data rather than identifier validation.

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 intended use case is implied by the description: validate a UID or VAT number and optionally verify its registration status. However, it never explicitly contrasts this with sibling tools or states when not to use it, and the only conditional guidance ('unless lookup=false') is about an option rather than tool selection.

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