Fix Protocol MCP

What slenderongithub/fix-protocol-mcp MCP server does

The slenderongithub/fix-protocol-mcp MCP server provides four operations for working with Financial Information eXchange (FIX) messages. It can decode raw tag=value messages, validate their structure and required fields, construct messages from supplied fields, and describe individual dictionary entries.

The bundled dictionary targets FIX 4.4 and covers common session and order-flow messages, including Logon, Heartbeat, TestRequest, ResendRequest, Reject, SequenceReset, Logout, NewOrderSingle, OrderCancelRequest, OrderCancelReplaceRequest, ExecutionReport, and OrderCancelReject. The project describes this as a curated subset rather than a complete FIX repository.

How it works

The server runs locally through stdio. Its processing does not depend on a remote API, network connection, or external credentials. A client sends tool calls to the local process, and the process returns decoded fields, validation results, constructed messages, or tag metadata.

The parser accepts FIX data delimited by SOH, |, or ^. Parsed fields include the numeric tag, field name, supplied value, and any known enum meaning. Validation checks standard header structure, field ordering, required and conditional fields for the message type, and the computed values for BodyLength(9) and CheckSum(10). Errors and warnings are returned separately.

For construction, callers can provide numeric tags or dictionary field names. Enum values may be supplied as codes or labels, such as "Side": "Buy". BeginString, BodyLength, and CheckSum are generated by the builder. Unknown tags and enum values are reported as warnings rather than automatically treated as hard failures.

Setup and configuration

Install the local project with pip install .. Installation provides the fix-protocol-mcp console script, which is the stdio server command. An MCP client configuration can start it with:

{
  "mcpServers": {
    "fix-protocol": {
      "command": "fix-protocol-mcp"
    }
  }
}

The slenderongithub/fix-protocol-mcp MCP server can also be started from source with python -m fix_protocol_mcp.server and PYTHONPATH set to src, as shown in the project documentation. Development setup uses pip install -e ".[dev]" followed by pytest.

Tools and capabilities

The slenderongithub/fix-protocol-mcp MCP server exposes these tools:

• parse_fix_message: Decodes a raw message into tags, names, values, and known enum meanings.
• validate_fix_message: Checks ordering, headers, required or conditional fields, BodyLength, and CheckSum, returning validity, errors, warnings, and checksum details.
• build_fix_message: Creates a FIX message from field inputs and calculates generated protocol fields.
• explain_fix_tag: Looks up a tag's name, data type, and enumerated values.

The underlying modules can also be imported as a plain Python library through parse, validate, build, and describe_tag; the MCP wrapper is separate from those core modules.

Limitations and notes

Coverage is limited to the bundled, curated FIX 4.4 dictionary. Messages, tags, or enum values outside that coverage may produce warnings and may not receive full semantic validation. The examples demonstrate Logon parsing, checksum failure detection, NewOrderSingle construction, and tag lookup, but they do not establish support for every FIX message variant.

Because the slenderongithub/fix-protocol-mcp MCP server is offline and self-contained, it does not connect to brokers, trading venues, market-data feeds, or other external systems. It analyzes and constructs message text; the provided material does not describe transmission or order execution features.