calculate_gstAdd GST to an amount or extract GST from a GST-inclusive amount. Current main rates: 0, 5, 18 and 40 percent (3% gold, 0.25% rough stones).
| Name | Required | Description | Default |
|---|---|---|---|
| rate | Yes | ||
| amount | Yes | ||
| inclusive | No | True if the amount already includes GST. |
| Name | Required | Description | Default |
|---|---|---|---|
| gst | Yes | Total GST. | |
| base | Yes | Amount before GST. | |
| cgst | Yes | ||
| sgst | Yes | ||
| total | Yes | Amount including GST. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish this as a safe, idempotent, read-only, closed-world computation, so the description is not obligated to restate that. It instead contributes domain knowledge the schema lacks: the current valid main rates and the special-case rates for gold and rough stones, which is genuinely useful behavior context for a pure calculation tool.
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 tight sentences with zero filler. The primary behavior (add vs extract) is front-loaded, and the rate enumeration follows as supporting detail.
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?
An output schema exists, so return values need not be explained, and the core add/extract semantics plus rate values are covered. The remaining gap is the percent-vs-fraction representation of `rate`, which matters for a calculator but is a narrow omission rather than a structural one.
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 coverage is only 33%, with just `inclusive` documented, so the description must carry more weight. Listing concrete rate values adds real meaning to the `rate` parameter, but it never clarifies whether rate should be supplied as 18 or 0.18, nor does it describe the `amount` parameter, leaving a genuine ambiguity for a calculation tool.
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 names a specific verb+resource pair and clearly distinguishes the two operations it supports: adding GST to an amount versus extracting GST from an inclusive amount. Neither sibling tools nor the title alone would convey that bidirectional behavior, though it does not explicitly contrast itself with siblings like compare_tax_regimes or salary_in_hand.
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 two modes are stated, which implies that the `inclusive` flag selects between them, but the description never says so directly or explains when to prefer this tool over tax-related siblings. Usage is inferable but not spelled out.
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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