smart-mcp-proxy 0.3.1
Smart MCP Proxy - A federating gateway for MCP servers with intelligent tool discovery
License: MIT
Requires Python: >=3.11.1
Keywords: ai, embedding, fastmcp, gateway, mcp, model-context-protocol, proxy, search, smart, tool-discovery

# Smart MCP Proxy

[![PyPI version](https://badge.fury.io/py/smart-mcp-proxy.svg)](https://badge.fury.io/py/smart-mcp-proxy)
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[![Python 3.11+](https://img.shields.io/badge/python-3.11+-blue.svg)](https://www.python.org/downloads/)

## Quick Start
install with pip:
```bash
pip install smart-mcp-proxy
```

## Cursor IDE Integration

To use mcpproxy in Cursor IDE, add this configuration to your `~/.cursor/mcp.json`:

```json
{
  "mcpServers": {
    "mcp-proxy": {
      "command": "mcpproxy",
      "env": {
        "MCPPROXY_CONFIG_PATH": "/Users/user/.cursor/mcp_proxy.json"
      }
    }
  }
}
```

Then create a separate `~/.cursor/mcp_proxy.json` with your actual(!) MCP servers:
(just an example of configuration, you can use any MCP servers you want)
```json
{
  "mcpServers": {
    "company-mcp": {
      "command": "uvx",
      "args": ["--from", "mcp-company-python@git+https://github.com/company/mcp-company.git", "company-mcp-server"],
      "env": {
        "COMPANY_TOKEN": "${COMPANY_TOKEN}",
        "PORT": "9090"
      }
    },
    "company-docs": {
      "url": "http://localhost:8000/mcp/"
    }
  }
}
```

**Important**: The `mcp_proxy.json` must be a different file than `mcp.json` to avoid circular proxy connections. The proxy configuration file has the same format as Cursor's MCP configuration but contains the actual MCP servers you want to federate.

## Google ADK Integration

To use mcpproxy with Google ADK, you can integrate it using the MCPToolset:

```python
from google.adk.tools.mcp_tool.mcp_toolset import MCPToolset, StdioServerParameters

proxy_tool = MCPToolset(
    connection_params=StdioServerParameters(
        command="mcpproxy",
        args=[],
        env={"MCPPROXY_CONFIG_PATH": "/Users/user/.cursor/mcp_proxy.json"}
    )
)
```

## Tip for better LLM results (copy-paste into your system/dev prompt):

```
When you see a tool named `retrieval_tools` in the MCP tool list, call it first.  
It returns the most relevant tools for the user’s request, helping you answer more accurately and concisely.
```

---

A federating gateway that sits between AI agents and multiple Model Context Protocol (MCP) servers, providing intelligent tool discovery and dynamic registration.

🌐 **Website**: [mcpproxy.app](https://mcpproxy.app)
📦 **PyPI**: [pypi.org/project/smart-mcp-proxy](https://pypi.org/project/smart-mcp-proxy/)
🔗 **GitHub**: [github.com/Dumbris/mcpproxy](https://github.com/Dumbris/mcpproxy)

## Features

- **Flexible Routing Strategies**: Two modes - `DYNAMIC` (tools registered on-demand) or `CALL_TOOL` (proxy-only execution)
- **Dynamic Tool Discovery**: Automatically discovers tools from multiple MCP servers
- **Intelligent Search**: Uses configurable embedding backends (BM25, HuggingFace, OpenAI) to find relevant tools
- **One-Click Tool Access**: Single `retrieve_tools` function that searches, registers, and exposes the top 5 most relevant tools
- **FastMCP Integration**: Built on FastMCP v2 for robust server runtime and client capabilities
- **Persistent Indexing**: SQLite + Faiss storage for fast tool lookup and change detection
- **MCP Spec Compliant**: Emits proper `notifications/tools/list_changed` events
- **Flexible Dependencies**: Optional dependencies for different backends to minimize install size

## Architecture

```
┌─────────────────┐    ┌─────────────────────────────────┐    ┌─────────────────┐
│   AI Agent      │───▶│     Smart MCP Proxy             │───▶│  MCP Servers    │
│                 │    │                                 │    │                 │
│ retrieve_tools()│    │ ┌─────────────┐ ┌─────────────┐ │    │ • company-prod  │
│                 │    │ │   Indexer   │ │ Persistence │ │    │ • company-docs  │
│ tool_1()        │◀───│ │   (BM25/    │ │  (SQLite +  │ │    │ • oauth-server  │
│ tool_2()        │    │ │ HF/OpenAI)  │ │   Faiss)    │ │    │ • ...           │
│ ...             │    │ └─────────────┘ └─────────────┘ │    │                 │
└─────────────────┘    └─────────────────────────────────┘    └─────────────────┘
```

## Quick Start

### 1. Installation

Choose your installation based on the embedding backend you want to use:

```bash
# Basic installation with BM25 (lexical search, no ML dependencies)
pip install smart-mcp-proxy

# Or with specific backends:
pip install smart-mcp-proxy[bm25]         # Explicit BM25 (same as basic)
pip install smart-mcp-proxy[huggingface]  # HuggingFace + vector search
pip install smart-mcp-proxy[openai]       # OpenAI embeddings + vector search
pip install smart-mcp-proxy[all]          # All backends available

# Development install
git clone https://github.com/Dumbris/mcpproxy.git
cd mcpproxy
pip install -e .[all]
```

The proxy will automatically check for required dependencies and provide helpful error messages if you try to use a backend without the required packages installed.

### 2. Start the Proxy

```bash
# Using the installed script
MCPPROXY_CONFIG_PATH=mcp_config.json mcpproxy
```

The proxy will:
1. Discover tools from all configured MCP servers
2. Index them using the chosen embedding backend
3. Start MCP server, by default transport is stdio, you can use MCPPROXY_TRANSPORT to change it to streamable-http or sse

## Routing Strategies

Smart MCP Proxy supports two routing strategies:

### DYNAMIC Mode
- **Behavior**: AI agent calls `retrieve_tools`, which searches and dynamically registers the most relevant tools as MCP tools
- **Tool Registration**: Tools become available in the MCP protocol after `retrieve_tools` call
- **Client View**: Sees both `retrieve_tools` and the registered tools (e.g., `company_create_user`, `storage_upload_file`)
- **Use Case**: Best for clients that can handle dynamic tool registration and notifications

### CALL_TOOL Mode (Default)
- **Behavior**: AI agent calls `retrieve_tools` to discover tools, then uses `call_tool` to execute them
- **Tool Registration**: No dynamic registration - tools are executed through the proxy
- **Client View**: Only sees `retrieve_tools` and `call_tool` tools
- **Use Case**: Better for clients with tool registration limits or simpler tool management

```bash
# Set routing strategy
export MCPPROXY_ROUTING_TYPE=DYNAMIC    # or CALL_TOOL (default)
```

## Output Truncation

To prevent context bloating from large tool outputs, you can configure output truncation:

```bash
# Truncate tool outputs to 2000 characters (disabled by default)
export MCPPROXY_TRUNCATE_OUTPUT_LEN=2000
```

When enabled, outputs exceeding the limit are truncated showing:
- First portion of the output
- `<truncated by smart mcp proxy>` marker  
- Last 50 characters of the output

This helps manage token usage while preserving both the beginning and end of outputs.

## Usage
### Cursor IDE

See example on the top of the [README.md](README.md) file.

### For AI Agents

**DYNAMIC Mode Usage:**
1. Call `retrieve_tools("user management")` 
2. Use the returned tools directly (e.g., `company_create_user`)

**CALL_TOOL Mode Usage:**
1. Call `retrieve_tools("user management")`
2. Call `call_tool("company_create_user", {"name": "john", "email": "john@example.com"})`

### Programmatic Usage

```python
from mcpproxy import SmartMCPProxyServer

proxy = SmartMCPProxyServer("config.json")
await proxy.start()

# Use the indexer directly
results = await proxy.indexer.search_tools("delete volume", k=3)
for result in results:
    print(f"{result.tool.name}: {result.score}")
```

## Project Structure

```
mcpproxy/
├── models/
│   └── schemas.py           # Pydantic models and schemas
├── persistence/
│   ├── db.py               # SQLite operations
│   ├── faiss_store.py      # Faiss vector storage
│   └── facade.py           # Unified persistence interface
├── indexer/
│   ├── base.py             # Base embedder interface
│   ├── bm25.py             # BM25 implementation
│   ├── huggingface.py      # HuggingFace embeddings
│   ├── openai.py           # OpenAI embeddings
│   └── facade.py           # Search and indexing interface
├── server/
│   ├── config.py           # Configuration management
│   └── mcp_server.py       # FastMCP server implementation
└── utils/
    └── hashing.py          # SHA-256 utilities for change detection
```

## Environment Variables

| Variable         | Values                        | Default | Description |
|------------------|-------------------------------|---------|-------------|
| `MCPPROXY_ROUTING_TYPE` | `DYNAMIC`, `CALL_TOOL`       | `CALL_TOOL` | Tool routing strategy |
| `MCPPROXY_EMBEDDER`    | `BM25`, `HF`, `OPENAI`        | `BM25`  | Embedding backend |
| `MCPPROXY_HF_MODEL`    | HuggingFace model name        | `sentence-transformers/all-MiniLM-L6-v2` | HF model |
| `MCPPROXY_TOP_K`       | Integer                       | `5`     | Number of tools to register |
| `MCPPROXY_TOOLS_LIMIT` | Integer                       | `15`    | Maximum number of tools in active pool |
| `MCPPROXY_TOOL_NAME_LIMIT` | Integer                   | `60`    | Maximum tool name length |
| `MCPPROXY_TRUNCATE_OUTPUT_LEN` | Integer               | -       | Truncate tool output to prevent context bloating (disabled by default) |
| `MCPPROXY_LIST_CHANGED_EXEC` | Shell command             | -       | External command to execute after tool changes (see [Client Compatibility](#client-compatibility)) |
| `MCPPROXY_DATA_DIR`    | Directory path                | `~/.mcpproxy` | Directory for database and index files |
| `MCPPROXY_CONFIG_PATH`| Path to config file           | `mcp_config.json` | Config file location |
| `MCPPROXY_HOST`     | Host to bind                  | `127.0.0.1` | Server host |
| `MCPPROXY_PORT`     | Port to bind                  | `8000`  | Server port |
| `MCPPROXY_TRANSPORT` | Transport to use              | `stdio` | Transport to use |
| `MCPPROXY_LOG_LEVEL` | Log level                     | `INFO`  | Logging level (DEBUG, INFO, WARNING, ERROR) |
| `MCPPROXY_LOG_FILE`  | File path                     | -       | Optional log file path |
| `MCPPROXY_RESET_DATA` | Boolean                      | `false` | Reset all data (useful when dimensions change) |

## Client Compatibility

### MCP Tool List Refresh Workaround

**This is only needed for DYNAMIC routing mode.** The default CALL_TOOL routing mode doesn't require `MCPPROXY_LIST_CHANGED_EXEC` since tools are not dynamically registered.

Some MCP clients (like Cursor IDE) don't properly handle the standard `tools/list_changed` notification when new tools are registered in DYNAMIC mode. As a temporary workaround, you can configure the proxy to execute an external command after tool changes to trigger client refresh.

#### For Cursor IDE

Set the `MCPPROXY_LIST_CHANGED_EXEC` environment variable to touch the MCP configuration file:

```bash
# For macOS/Linux
export MCPPROXY_LIST_CHANGED_EXEC="touch $HOME/.cursor/mcp.json"

# For Windows (PowerShell)
$env:MCPPROXY_LIST_CHANGED_EXEC = "cmd /c copy `"$HOME\.cursor\mcp.json`" +,,"
```

This causes Cursor to detect the config file change and refresh its tool list.

#### How it Works

1. When you call `retrieve_tools`, the proxy registers new tools
2. Standard `tools/list_changed` notification is sent (proper MCP way)
3. If `MCPPROXY_LIST_CHANGED_EXEC` is set, the command is executed asynchronously
4. The command triggers the MCP client to refresh its tool list

#### Security Note

⚠️ **Important**: The command in `MCPPROXY_LIST_CHANGED_EXEC` is executed with shell privileges. Only use trusted commands and never set this variable to user-provided input.

#### When Not to Use

- Your MCP client properly handles `tools/list_changed` notifications
- You're using the proxy programmatically (not through an MCP client)
- Security policies prohibit executing external commands

This feature is disabled by default and only executes when explicitly configured.

## Contributing

We welcome contributions! Please see our [GitHub repository](https://github.com/Dumbris/mcpproxy) for:

- 🐛 **Bug Reports**: [Submit an issue](https://github.com/Dumbris/mcpproxy/issues)
- 💡 **Feature Requests**: [Start a discussion](https://github.com/Dumbris/mcpproxy/discussions)
- 🔧 **Pull Requests**: Fork the repo and submit a PR

### Development Setup

```bash
git clone https://github.com/Dumbris/mcpproxy.git
cd mcpproxy
pip install -e .[dev,all]
pytest tests/
```

## License

This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.