validate_tan

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety is well-covered. The description adds that the return includes 'decoded segments,' which is useful but still vague about the exact shape of the result. It does not conflict with the annotations, but it also doesn't fully disclose validation behavior for invalid inputs.

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 compact, front-loaded, and formatted with clear sections: purpose, usage context, args, and returns. It lacks filler. The only minor redundancy is repeating the tan parameter description already present in the schema, but this is acceptable and doesn't hurt scannability.

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 single-parameter validation tool with rich annotations and an output schema, this description is adequate. It tells the agent what the TAN is, when to use the tool, and that the result is a validation result with decoded segments. Additional detail about invalid-input behavior would strengthen it but is not essential here.

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 description coverage is 100%, so the parameter is fully documented in the input schema. The description does repeat that `tan` is a 10-character TAN, but adds only marginal semantic value beyond the schema. A baseline score of 3 fits because the schema carries the documentation weight.

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 identifies the tool's purpose: validating TAN format for TDS compliance. The verb 'Validate' plus the explicit resource 'TAN (Tax Deduction Account Number)' leaves no ambiguity about what the tool does, and it naturally distinguishes this from sibling validation tools for PAN, GSTIN, Aadhaar, etc.

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 states exactly when to use the tool: 'Use when verifying TAN format for TDS compliance.' This provides clear, specific context. It does not explicitly list when not to use it or name alternative tools, but given the clearly distinct resource type, this is a minor omission.

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