fp-conv-mcp

A Model Context Protocol (MCP) server that gives AI agents direct, local tools for floating-point conversions. It is the server-side companion to the fp-conv web app and reuses the same conversion library.

Encode, decode, and convert numbers across FP32, FP64, FP16, BF16, TF32, FP8, FP6, FP4, signed/unsigned ints, and custom formats. Supports rounding modes and calculates precision loss.

Tools

| Tool | Description | | --- | --- | | list_formats | List all available format presets (keys, names, categories, parameters). | | get_format_info | Get detailed information about a format (bias, range, special-value support). | | encode_number | Encode a decimal value (or Infinity/NaN) into a format. Returns binary, hex, and components. | | decode_bits | Decode a binary or hex bit-pattern into a format. Returns the decimal value and components. | | convert_format | Convert a value from one format to another. |

Formats

All tools accept either a preset key (string) or a custom format object.

Preset keys

| Category | Keys | | --- | --- | | IEEE 754 | "fp64", "fp32", "fp16" | | ML | "bf16", "tf32" | | OCP | "fp8_e5m2", "fp8_e4m3", "fp6_e3m2", "fp6_e2m3", "fp4_e2m1" | | Integer | "int32", "uint32", "int16", "uint16", "int8", "uint8", "int4", "uint4" |

Custom formats

For floating-point:

{ "signBits": 1, "exponentBits": 5, "mantissaBits": 10, "bias": 15, "hasInfinity": true, "hasNaN": true }

| Field | Required | Description | | --- | --- | --- | | signBits | yes | Number of sign bits (typically 1) | | exponentBits | yes | Number of exponent bits | | mantissaBits | yes | Number of mantissa (fraction) bits | | bias | no | Exponent bias; defaults to 2^(exponentBits-1) - 1 | | hasInfinity | no | Whether the format can represent ±Infinity (default true) | | hasNaN | no | Whether the format can represent NaN (default true) |

For integers:

{ "bits": 16, "signed": true }

| Field | Required | Description | | --- | --- | --- | | bits | yes | Total bit width (1–64) | | signed | yes | true for signed two's-complement, false for unsigned |

Precision note: values are computed with JavaScript doubles, so formats wider than 53 significant bits (e.g. 64-bit integers or mantissas above 52) are supported but may round at the extremes of their range.

Client configuration

Refer to the following examples with details on how to configure the MCP server:

VS Code (.vscode/mcp.json)

{
  "servers": {
    "fp-conv": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "fp-conv-mcp"]
    }
  }
}

Claude Code

claude mcp add fp-conv -- npx -y fp-conv-mcp

GitHub Copilot CLI

copilot mcp add fp-conv -- npx -y fp-conv-mcp

Cursor (.cursor/mcp.json) / Windsurf / Claude Desktop

{
  "mcpServers": {
    "fp-conv": {
      "command": "npx",
      "args": ["-y", "fp-conv-mcp"]
    }
  }
}

Antigravity (~/.gemini/config/mcp_config.json)

{
  "mcpServers": {
    "fp-conv": {
      "command": "npx",
      "args": ["-y", "fp-conv-mcp"]
    }
  }
}

Streamable HTTP (local only)

Alternatively, the server can run a local Streamable HTTP endpoint:

npm install -g fp-conv-mcp
fp-conv-mcp --http --host 127.0.0.1 --port 3001
# endpoint: http://127.0.0.1:3001/mcp

Security: The HTTP transport has no authentication and binds to 127.0.0.1 by default. Do not bind it to a non-loopback interface unless you add your own authentication and understand the implications.

Usage

Once connected, you can ask an agent things like:

• "Encode 3.14159 as bf16 and show the binary."
• "What does the fp16 bit-pattern 0x3E00 decode to?"
• "Convert 0.1 from fp32 to fp8 e4m3 and tell me the precision loss."
• "List all supported formats."

Debugging

Use the MCP Inspector:

npx @modelcontextprotocol/inspector npx fp-conv-mcp

Then open the Tools tab, click List Tools, and try any tool.

Development

This package lives in the fp-conv repository as an npm workspace. The published bundle (dist/index.js) inlines the shared conversion engine (lib/floating-point.js) and tool definitions (src/webmcp.js) from the repo root via esbuild, keeping a single source of truth.

npm install                         # from the repo root
npm run build --workspace fp-conv-mcp
npm test  --workspace fp-conv-mcp

License

MIT © Spencer Williams