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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, fully covering safety. The description adds the precise computation behavior (Luhn check digit) and input constraints (first 14 digits). No contradictions. With high annotation coverage, the description adds useful but not critical context.

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 sentence contains all essential information: action, input scope, algorithm, and use case. No filler or redundancy. Excellent conciseness.

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 tool with no output schema, the description is fully complete. It explains what the tool does, when to use it, and what input is expected. The output (a single check digit) is implicit and does not require further explanation.

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 coverage is 100% with a clear description of the 'digits' parameter ('The first 14 digits (no check digit).'). The tool description reinforces this but does not add new semantic info beyond the schema. Baseline 3 is appropriate.

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 action ('Compute'), the algorithm ('Luhn check digit'), the input scope ('first 14 digits of an IMEI'), and the use case ('complete or repair an IMEI'). It effectively distinguishes from sibling validate_imei.

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 states the use case ('use to complete or repair an IMEI'). While it does not explicitly contrast with validate_imei or other alternatives, the context of sibling tools makes the differentiation clear. A slightly more explicit alternative mention would elevate to a 5.

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