MCP All-in-One Server

by Arnie936

Overview Schema Source Related Servers Discussions Admin

Python

Local

subtract

Calculate the difference by subtracting the second number from the first.

Instructions

Subtract b from a

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

Implementation Reference

calculator_server/server.py:186-189 (handler)
The subtract tool handler function. Registered with @mcp.tool() decorator, takes two floats (a, b) and returns a - b.
```
@mcp.tool()
def subtract(a: float, b: float) -> float:
    """Subtract b from a"""
    return a - b
```
calculator_server/server.py:186-186 (registration)
The @mcp.tool() decorator on line 186 registers the subtract function as an MCP tool.
```
@mcp.tool()
```

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0May 16, 2026

TDQS

A4.3/5.0

Behavior4/5

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

With no annotations, the description carries the behavioral disclosure burden. It clearly states that the operation subtracts b from a, making the operand order explicit. For a pure numeric operation with no side effects, this is sufficient, though it does not discuss edge cases like non-finite numbers.

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 four words long, front-loaded with the verb, and contains no filler or redundant information. Every word earns its place.

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?

For a simple, pure arithmetic operation, the description fully covers what an agent needs to invoke it correctly. The operands are identified, the order is explicit, and the output schema exists to document the return value.

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

Parameters4/5

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

The schema only provides titles 'A' and 'B' with no description coverage, so the description must add meaning. 'Subtract b from a' clarifies the critical ordering: parameter b is the subtrahend and parameter a is the minuend, which is essential for correct invocation.

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 uses a specific verb ('Subtract') and names the operands ('b from a'), making the operation unambiguous. It is instantly distinguishable from the sibling tools add, multiply, and divide.

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?

The description implies the appropriate usage for subtraction, but it does not explicitly state when to choose this tool over alternatives or provide any exclusion conditions. An agent can infer the use case from the operation name, but no targeted guidance is given.

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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