HOLCO FEC Controls

Deterministic, explainable controls for synthetic French accounting export (FEC-like) data, exposed as a local MCP server for Claude and other compatible clients.

Deterministic when possible. AI when necessary. Human when accountable.

This repository is a clean-room public example. It contains no production code, customer data, credentials or internal HOLCO endpoints. It is not tax advice and does not certify legal or fiscal compliance.

Controls

required column presence;
parseable YYYYMMDD dates;
decimal debit and credit amounts;
debit/credit balance for every journal entry;
duplicate-line detection.

Every finding contains a stable code, severity, line or entry reference and a human-readable explanation. The AI client presents the result; it does not silently change the deterministic verdict.

Control contract

The server separates planning from execution:

plan_fec_control declares controls, assumptions and decisions that require human input;
analyze_fec_text runs every applicable deterministic control;
the result binds evidence to the source with SHA-256 hashes and locators, without echoing accounting rows;
every planned control is reported as PASS, REVIEW, FAIL or NOT_RUN.

Business plausibility is deliberately NOT_RUN until an entity-approved policy or benchmark is provided. A generic model opinion cannot turn a failed accounting invariant into a pass. Consequently, a technically clean file has a deterministic_outcome of PASS but remains globally REVIEW while the declared business check is not run.

Run the tests

python -m pip install -e '.[mcp]'
python -m unittest discover -s tests -v

Connect to Claude Desktop

After installation, add this local server to your Claude Desktop MCP configuration:

{
  "mcpServers": {
    "holco-fec-controls": {
      "command": "holco-fec-mcp"
    }
  }
}

Restart Claude Desktop, then ask it to call analyze_fec_text with FEC content. The tool accepts text rather than a filesystem path, preventing unrestricted file reads by the server. Keep real accounting exports within an environment whose confidentiality rules you control.

MCP tools

list_fec_controls: returns the public control catalogue.
plan_fec_control: previews scope, assumptions and human decisions.
analyze_fec_text: analyses tab-separated content and returns structured results, evidence hashes, completeness and the stop reason.