VAT code description

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is known. The description adds the optional column behavior, which is a meaningful behavioral trait not present in the annotations. It does not describe error handling or return format, but for a simple read operation this is acceptable.

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 with no wasted words. The first sentence states the primary purpose, and the second covers the optional parameter. Front-loaded and clearly structured.

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 retrieval tool with one required parameter, the description, combined with full schema coverage and read-only annotations, provides sufficient context. No output schema exists, but the return value (a description string) is implied by the tool's name and description, so no additional detail is needed.

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 covers all parameters with descriptions (100% coverage), so baseline is 3. The description adds semantic value by explaining that the 'column' parameter overrides the default Description output, which links the parameter to the tool's primary behavior and clarifies its role beyond the schema text.

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 tool's function: 'Return the description of a VAT code.' It specifies a concrete action and resource, and the optional column detail distinguishes it from sibling tools like banana_vatcodes, which likely lists VAT codes rather than retrieving a single description.

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 implies usage (when you need a VAT code description) but does not explicitly mention when to use this tool versus alternatives like banana_vatcodes, nor does it provide exclusions or alternatives. The optional column note gives a usage option but no strategic guidance.

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