validate_gln

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

With no annotations, the description carries the full burden. It discloses the algorithmic nature (check digit validation), describes the output (issuing country), and explicitly states what it does not do (confirm registration). This provides good insight into behavior, though it could mention if any external calls or auth are needed (likely none).

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 three sentences with zero wasted words. It front-loads the usage instruction ('USE THIS to verify...'), then details what it does and its limitations. Every sentence adds value.

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 simple validation tool with one parameter and no output schema, the description covers everything needed: what it validates, how (check digit), what it returns (country), and limitations (structure only, not registration). No gaps.

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 schema has 100% coverage with a decent description. The tool description adds valuable context: defines GLN as 'GS1 Global Location Number' and explains its purpose in supply chains and EDI. This extra context clarifies the parameter's meaning beyond 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 clearly states the verb 'verify' and the resource 'GLN'. It specifies exact operations: checks 13-digit GS1 mod-10 check digit and returns issuing country. Distinguishes from siblings by specifying it validates GLN structure only, not registration status.

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 explicitly advises using the tool 'before relying on a GLN', providing clear when-to-use guidance. It also states that it validates structure only, not registration, which implies limitations. However, it does not explicitly mention when not to use or compare to alternative tools, though sibling tools cover different identifier types.

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