ACG MCP Server

Standalone MCP server for the Audited Context Generation (ACG) Protocol — verifiable fact-checking and grounded RAG via MongoDB.

ACG provides a dual-layer standard for veracity assurance:

• UGVP (Layer 1): Atomic fact grounding with Claim Markers and Source Hash Identity (SHI)
• RSVP (Layer 2): Logical synthesis verification with Relationship Markers

Features

• Index URLs → Extract text, chunk by sentences, generate embeddings, store in MongoDB
• Search Sources → Semantic (vector) + keyword search across indexed content
• Check Indexed → Confidence-scored lookup to avoid unnecessary web_fetch calls
• Generate Grounded Text → Create verifiable output with inline Claim Markers
• Verify Claims → Re-fetch sources, fuzzy-match claims against source text
• Build VAR → Generate machine-readable Veracity Audit Registry (SSR + RAR)
• Crawl & Index → BFS URL discovery + automatic ACG indexing pipeline
• Reset Database → Drop all ACG collections (with confirmation guard)

Available Tools

Database Collections

The server uses a standard MongoDB collection structure:

Indexes are auto-created on first connection.

Requirements

• Python 3.11+
• MongoDB instance (local or Atlas)
  • Atlas Vector Search is optional — falls back to keyword search if no embedding model

Installation

There are two ways to install — choose based on your use case:

Option A: Local development (editable install)

For local development where you'll edit the code, install in editable mode:

# Clone the repo
git clone https://github.com/Kos-M/acg_mcp.git
cd acg_mcp

# Install globally in editable mode (recommended for agents/CLI usage)
pip install -e .

# Or use a venv:
# python -m venv venv && source venv/bin/activate && pip install -e .

This makes the acg-mcp command available system-wide (or venv-wide), so you can run it from any directory.

Option B: Using the source directly

git clone https://github.com/Kos-M/acg_mcp.git
cd acg_mcp
pip install -r requirements.txt
# Then run with: python -m src.server

Configuration

Copy .env.sample to .env and configure:

# MongoDB connection string (required)
MONGO_URI=mongodb://localhost:27017

# MongoDB database name (optional, default: acg_protocol)
MONGO_DB=acg_protocol

# Embedding model cache directory (optional)
EMBEDDING_CACHE_DIR=

For MongoDB Atlas:

MONGO_URI=mongodb+srv://<user>:<password>@<cluster>.mongodb.net/acg_protocol?retryWrites=true&w=majority

Usage

Run the MCP server (stdio transport)

After editable install (recommended for global use):

# Works from ANY directory — no venv activation needed if installed system-wide
acg-mcp

Without installing the CLI (source directory only):

cd /path/to/acg_mcp
python -m src.server

Connect from an MCP client

The server communicates over stdio. These examples work for both Claude Desktop and Opencode (same mcpServers JSON format).

Global install (recommended for agents & tools)

After pip install -e ., the acg-mcp command is available globally. Use it directly in your MCP config — no path needed:

{
  "mcpServers": {
    "acg-mcp": {
      "command": "acg-mcp",
      "env": {
        "MONGO_URI": "mongodb+srv://..."
      }
    }
  }
}

Running from source directory

If you haven't installed the CLI, use the full path:

{
  "mcpServers": {
    "acg-mcp": {
      "command": "python",
      "args": ["-m", "src.server"],
      "env": {
        "MONGO_URI": "mongodb+srv://..."
      }
    }
  }
}

Important: When using python -m src.server, run the MCP client from the project root (/path/to/acg_mcp) or set cwd in the MCP config.

Config locations

Usage from other tools & agents

Once installed globally with pip install -e ., any tool or agent on the machine can use acg-mcp by referencing it in their MCP configuration.

Example: WEBFORGE agent setup

Add to your agent's MCP config (e.g., ~/.opencode/mcp.json):

{
  "mcpServers": {
    "acg-mcp": {
      "command": "acg-mcp",
      "env": {
        "MONGO_URI": "mongodb://localhost:27017"
      }
    }
  }
}

The agent can then call ACG tools directly:

• acg_check_indexed() — Check if answers exist in indexed sources
• acg_index_url() — Index new URLs
• acg_verify_claims() — Verify grounded text claims
• acg_search_sources() — Search indexed knowledge base

Passing environment variables

Pass MONGO_URI and other config via the env field in the MCP config. The server also loads .env from the project directory if present.

License

MIT