Simple MCP Server
A simple Model Context Protocol (MCP) server that provides value lookup operations. This server implements a basic key-value store that can be accessed by MCP-compatible AI assistants and clients.
Features
- In-memory key-value store: Store and retrieve data during the session
- JSON support: Automatically parses and formats JSON values
- Multiple operations: Get, set, delete, list, and clear operations
- MCP protocol compliance: Uses the standard MCP protocol for communication
- Easy integration: Can be used with any MCP-compatible client
Available Tools
The server provides the following tools that can be called by MCP clients:
get_value
Retrieve a value from the store by key.
- Parameters:
key(string) - The key to look up - Returns: The value associated with the key, or an error message if not found
set_value
Store a key-value pair in the store.
- Parameters:
key(string) - The key to storevalue(string) - The value to store (automatically parsed as JSON if valid)
- Returns: Confirmation message
delete_value
Remove a key-value pair from the store.
- Parameters:
key(string) - The key to delete - Returns: Confirmation message
list_keys
List all keys currently in the store.
- Parameters: None
- Returns: A formatted list of all keys
clear_values
Clear all key-value pairs from the store.
- Parameters: None
- Returns: Confirmation message
get_store_info
Get information about the current state of the store.
- Parameters: None
- Returns: Store statistics and sample keys
Installation
- Clone this repository:
git clone https://github.com/jmgress/simple-mcp.git
cd simple-mcp
- Install dependencies:
pip install -e .
Usage
Running the Server
Start the MCP server using stdio transport:
simple-mcp-server
Or run directly with Python:
python -m simple_mcp.server
Testing the Server
You can test the server functionality using the included test script:
python test_server.py
This will demonstrate all available operations and show you how the server responds.
Using with MCP Clients
The server can be used with any MCP-compatible client. Configure your client to connect to this server using stdio transport.
Example client configuration (varies by client):
{
"servers": {
"simple-mcp": {
"command": "simple-mcp-server",
"transport": "stdio"
}
}
}
Example Operations
Here are some example operations you can perform:
# Store a simple string value
set_value(key="greeting", value="Hello, World!")
# Store JSON data
set_value(key="user", value='{"name": "Alice", "age": 30}')
# Retrieve values
get_value(key="greeting") # Returns: "Hello, World!"
get_value(key="user") # Returns formatted JSON
# List all keys
list_keys() # Returns: "Keys in store (2 total): greeting, user"
# Get store information
get_store_info() # Returns current store statistics
# Clean up
delete_value(key="greeting")
clear_values() # Removes all data
Architecture
The server is built using:
- FastMCP: A high-level MCP server framework
- JSON-RPC 2.0: For client-server communication
- Pydantic: For data validation and serialization
- asyncio: For asynchronous operation
The value store is currently in-memory only, meaning data is lost when the server restarts. This makes it suitable for temporary storage and demonstration purposes.
Development
To set up for development:
# Install in development mode with dev dependencies
pip install -e ".[dev]"
# Run tests
python test_server.py
# Format code
black src/
# Lint code
ruff check src/
License
This project is licensed under the MIT License - see the LICENSE file for details.
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