gstin_validateValidate a 15-character Indian GSTIN via its mod-36 checksum and extract the state code for tax registration verification.
Validate an Indian GSTIN using its mod-36 checksum and extract the state code.
| Name | Required | Description | Default |
|---|---|---|---|
| gstin | Yes | 15-character GSTIN to validate. |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full behavioral burden. It discloses the validation method (mod-36 checksum) and an additional output (state code extraction), which goes beyond basic validation. However, it doesn't specify error behavior for invalid GSTINs or return format details (though output schema exists).
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?
Single sentence, front-loaded with the core action (Validate) and key detail (mod-36 checksum), plus secondary benefit (extract state code). Zero waste.
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 tool has one parameter, full schema coverage, and an output schema, the description is sufficient. It adds value by disclosing the validation algorithm and state code extraction. Minor gap: no error handling details or alternative routing, but not critical for a simple validation tool.
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%, and the description adds no parameter-specific information beyond what the schema provides. The single parameter 'gstin' is fully documented in the schema. Baseline 3 is appropriate when schema does the heavy lifting.
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?
States a specific verb (Validate) and resource (Indian GSTIN), plus secondary action (extract state code). Clearly distinguishable from siblings like gst_split or gst_from_inclusive which perform different GST operations.
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 this tool is for validating GSTINs, but provides no explicit when-to-use guidance or mentions of alternatives. For a domain with multiple GST-related siblings, more routing guidance would help.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.