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

With no annotations, the description must carry the full transparency burden. It discloses the tool's core behavior (validation and agency identification) but does not clarify whether it is read-only, how invalid input is handled, or what the response structure looks like. These aspects are left inferred from the tool's name and nature.

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 concise sentences with no filler; the first states the validation purpose and regulatory reference, the second adds the agency identification output. Every word earns its place.

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 single-parameter validation tool, the description adequately covers purpose, regulatory basis, and an additional output detail. It does not specify return format or error behavior due to the absence of an output schema, but the tool's simplicity makes these minor gaps acceptable.

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 fully describes the single 'udi' parameter as 'UDI string to validate' (100% coverage). The tool description adds regulatory context but no additional parameter-level detail such as formatting examples or optionality, so it meets the baseline without exceeding it.

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 the specific verb 'Validate' and names the resource 'UDI format' with reference to MDR Art. 27, clearly distinguishing it from sibling tools that handle adverse events, classification, or other regulatory checks.

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 makes the use case explicit: validating UDI format and identifying issuing agency. However, it does not mention when to prefer this tool over alternatives or any exclusions, so it lacks explicit when-not-to-use guidance.

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