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

With no annotations, the description carries the full burden and does well: it explicitly discloses 'No persistence of the raw value' and 'Stateless validator: records no decision and leaves no dashboard timeline trace.' This clearly communicates side-effect-free behavior, which is valuable beyond the basic operation.

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 two sentences, front-loaded with the core purpose and then behavioral guarantees. Every word adds value; there is no redundancy or filler.

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?

Given the lack of an output schema, the description adequately explains the returns (masked form, validity, reference token) and the stateless nature. It doesn't detail error handling or the token's purpose, but for a simple one-parameter tool, this is largely complete.

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 0% coverage for the parameter 'aadhaar', and while the description identifies it as 'an Aadhaar number', it does not provide details like 12-digit format or constraints. The mention of Verhoeff-validate adds some semantic hint about the validation logic, but it does not fully compensate for the schema's lack of information.

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: 'Mask + Verhoeff-validate an Aadhaar number.' It specifies the resource (Aadhaar number), the actions (mask and validate), and the outputs (masked form, validity, reference token), distinguishing it from siblings like cpf_validate or gstin_validate.

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 for masking and validating Aadhaar numbers, but it does not explicitly compare with alternatives or state when not to use. There is no mention of sibling tools, so the agent must infer the appropriate use case from the purpose alone.

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