CALCULATE_MCP

calculate_decimal

Perform high-precision decimal arithmetic on string inputs to avoid IEEE-754 rounding errors. Set precision from 1 to 200 significant digits for accurate add, divide, sqrt, and other operations.

Instructions

Perform high-precision decimal arithmetic without IEEE-754 surprises. Inputs are decimal strings and precision can be 1-200 significant digits.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "operation": "<operation>",
      "a": "<a>"
    },
    "name": "calculate_decimal"
  }
}

Input Schema

Name	Required	Description	Default
`a`	Yes
`b`	No
`operation`	Yes
`precision`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.2.0Sep 14, 2026

TDQS

B3.4/5.0

Behavior3/5

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

With no annotations, the description carries the full burden. It usefully clarifies that inputs are decimal strings and that precision means significant digits (1-200), but says nothing about error behavior (divide by zero, sqrt of negatives), whether the result is rounded/truncated, or the return format.

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?

Two tightly written sentences with the core capability front-loaded and the input/precision contract immediately after. No filler or repetition of the tool name.

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

Completeness2/5

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

Four parameters at 0% schema coverage, no annotations, and no output schema, yet the description is only two sentences. It omits operand requirements per operation, failure modes, and result format — significant gaps for an arithmetic tool whose behavior differs by enum value.

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 0%, so the description has to compensate. It explains the type of 'a'/'b' (decimal strings) and the meaning and range of 'precision' as significant digits, which is real added value, but it never explains that 'b' is required for binary operations while 'sqrt' needs only 'a'.

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

Purpose4/5

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

The description gives a specific verb ('Perform') and a precise resource ('high-precision decimal arithmetic'), and the IEEE-754 clause narrows the scope well. It does not, however, differentiate itself from siblings like calculate_expression or calculate_percentage, which an agent could easily confuse it with.

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

Usage Guidelines3/5

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

'Without IEEE-754 surprises' implies the use case — reach for this when exact decimal results matter — which is genuine implied guidance. But it names no alternative and gives no explicit when/when-not rules against the twelve sibling calculators.

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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