gstAdd or extract GST — India slabs (5/12/18/28), Australia/NZ/Singapore/Canada rates. GST both directions — exclusive to inclusive and back — with the Indian slab structure (5/12/18/28%) and the single-rate systems (Australia 10%, New Zealand 15%, Singapore 9%, Canada 5% federal) built into the rate picker.
| Name | Required | Description | Default |
|---|---|---|---|
| mode | No | Direction | add |
| rate | No | GST rate | 18 |
| amount | No | Amount |
Changes observed during successful MCP inspections.
Input schema / properties / rate / enumPrevious value: -[
- "5",
- "12",
- "18",
- "28",
- "10",
- "15",
- "9"
-]New value: +[
+ "5",
+ "12",
+ "18",
+ "28",
+ "10",
+ "15",
+ "9",
+ "13"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the safe read-only nature is covered. The description adds context about the built-in rate structures, which is useful. However, it fails to disclose what the tool returns (e.g., just the GST amount or total) and omits the '13%' rate option that appears in the schema.
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 redundant: 'Add or extract GST' and 'GST both directions — exclusive to inclusive and back' say the same thing, and the rate lists are repeated in both sentences. It could be condensed to one sentence without losing information.
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?
The tool is simple with three optional parameters and no output schema. The description explains core behavior and rate options but does not describe the output format or edge cases like the 13% rate. It is adequate but leaves notable gaps.
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 100% with basic descriptions for mode, rate, and amount. The description adds meaning by explaining the rate sources (e.g., Australia 10%, India slabs), helping the user pick a rate. Yet it doesn't clarify the '13' rate likely representing Canadian HST, leaving a gap.
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's purpose with a specific verb ('Add or extract GST') and resource (GST), and distinguishes it from siblings by naming the supported rate structures (India slabs, Australia/NZ/Singapore/Canada). The scope is explicit, making it obvious what the tool does.
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?
No guidance is given on when to use this tool versus alternatives like the 'vat' tool. The description only explains what the tool does, not in what circumstances it should be chosen or excluded.
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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