calculator_mcp

subtract

Calculate the difference between two numbers by taking the second value away from the first.

Instructions

Subtract the second number from the first.

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": {
      "a": "<a>",
      "b": "<b>"
    },
    "name": "subtract"
  }
}

Input Schema

Name	Required	Description	Default
`a`	Yes
`b`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 13, 2026

TDQS

B3.3/5.0

Behavior3/5

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

No annotations are provided, so the description carries the full behavioral burden. It does disclose the operand ordering ('second number from the first'), which is the key behavioral detail for subtraction, but it does not mention result type, error behavior, or any other runtime characteristics.

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?

A single, front-loaded sentence with no wasted words. It communicates the core operation directly and is appropriately sized for a simple arithmetic tool.

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

Completeness3/5

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. For a two-parameter arithmetic tool this is minimally adequate, but the description could explicitly map 'first'/'second' to 'a'/'b' to remove the only real ambiguity in calling 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 coverage is 0%, so parameter semantics must come from the description. It maps 'first' and 'second' to the two operands, implying a minus b, but does not explicitly bind those terms to the parameter names 'a' and 'b', leaving a slight ambiguity.

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 states a specific mathematical operation (subtraction) with explicit operand order (second from first), which is clearer than a bare name. It lacks any sibling differentiation, though the sibling names (add, divide, multiply) make the distinction obvious without extra text.

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

Usage Guidelines2/5

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

No guidance is given about when to use this tool versus alternatives like add or divide. The description only states the operation, not the context or conditions for selecting it.

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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