TrueCalci

India GST (regular scheme: CGST, SGST, IGST)

gst_regular

Read-onlyIdempotent

Calculate Indian GST on a supply under the regular scheme: CGST + SGST for an intra-state supply, IGST for an inter-state supply, export or SEZ supply, with optional compensation cess, reverse charge and input tax credit eligibility (Sections 9 and 16-17, CGST Act 2017; Section 5, IGST Act 2017).

Behavior: Deterministic, idempotent calculation with zero external side effects. The rate must be one notified in the GST rule pack in force on as_of_date; the engine refuses a rate the pack does not contain rather than assume one. Exclusive mode adds tax to the amount; inclusive mode extracts it. Returns taxable value, CGST, SGST, IGST, cess, total tax and invoice total.

Usage Guidelines: Use for a registered person under the regular scheme. Do not use for a composition-scheme taxpayer; use gst_composition instead.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`amount`	Yes	Supply value in INR (the taxable value in exclusive mode, the tax-inclusive total in inclusive mode).
`is_rcm`	No	Tax payable by the recipient under reverse charge (Section 9(3)/9(4)).
`as_of_date`	Yes	Civil date YYYY-MM-DD. Selects the rule pack in force on that date. Required: the engine will not assume a date.
`supply_type`	No	Intra-state (CGST + SGST), inter-state (IGST), export or SEZ supply. If omitted, derived from supplier_state and place_of_supply when both are given.
`cess_percent`	No	Compensation cess in percent, where applicable.	0
`itc_eligible`	No	Whether the recipient may claim input tax credit (false for a Section 17(5) blocked credit).
`rate_percent`	Yes	GST rate in percent. Must be a rate notified in the rule pack in force on as_of_date.
`supplier_state`	No	Supplier's state: 2-digit GST state code or state name.
`place_of_supply`	No	Place of supply: 2-digit GST state code or state name.
`calculation_mode`	No	'exclusive' adds GST to amount; 'inclusive' extracts GST from amount.	exclusive

Schema Changelog

Changes observed during successful MCP inspections.

AddedSep 26, 2026
RemovedSep 24, 2026
AddedSep 11, 2026

TDQS

A4.7/5.0

Behavior5/5

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

The description discloses deterministic, idempotent behavior with no side effects, which aligns with the idempotentHint and destructiveHint annotations. It further adds what a plain annotation can't: the engine refuses unknown rates, exclusive vs inclusive mode adds or extracts tax, and lists the return fields. This is rich behavioral context beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is structured with a purpose sentence followed by clear 'Behavior' and 'Usage Guidelines' sections. Every sentence earns its place—no fluff, and the purpose is front-loaded before behavioral and usage details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With 10 parameters, 100% schema coverage, and no output schema, the description compensates by listing the return fields (taxable value, CGST, SGST, IGST, cess, total tax, invoice total). It also clarifies the rate-rule-pack constraint and mode semantics, so an agent has everything needed to call it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all 10 parameters are already documented in the input schema. The description adds only marginal value (e.g., explaining exclusive/inclusive mode, which the schema already covers for calculation_mode). Since the schema does the heavy lifting, the baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb (calculate) and resource (Indian GST under the regular scheme), and immediately distinguishes intra-state (CGST+SGST) from inter-state/export/SEZ (IGST) supplies. It names the sibling gst_composition, which disambiguates it from other tools without needing to inspect schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly states when to use it (registered person under the regular scheme) and when not to (composition-scheme taxpayer), and names the alternative gst_composition. This is clear routing guidance that leaves no inference to the agent.

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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