Validate a GSTIN structurally (state code + PAN + entity-sequence + Mod-36 check digit). Note: this checks structure, not whether the GSTIN is currently active — for active-status, an authorized GST API call is required.
| Name | Required | Description | Default |
|---|---|---|---|
| gstin | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations present, but the description fully discloses the tool's limitation (structure-only) and does not overpromise, with no contradictions.
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, no redundancy, front-loaded with the primary function and immediate clarification of scope.
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 a simple one-parameter tool with no output schema, the description covers all necessary context: what it does, what it doesn't do, and how to complement it.
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?
Only one parameter 'gstin' with 0% schema coverage. The description explains its purpose (validate GSTIN structure) but does not specify format details (e.g., length, pattern) beyond the structural breakdown.
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 validates a GSTIN structurally, listing the components (state code, PAN, entity-sequence, check digit), distinguishing it from active status 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?
Explicitly notes that this checks structure only, not active status, and directs users to an authorized GST API for active-status checks, providing clear when-to-use and 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.
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