Configuration File

MCPProxy uses a JSON configuration file located at ~/.mcpproxy/mcp_config.json.

Location

Platform	Default Location
macOS	~/.mcpproxy/mcp_config.json
Linux	~/.mcpproxy/mcp_config.json
Windows	%USERPROFILE%\.mcpproxy\mcp_config.json

Complete Reference

{
  "listen": "127.0.0.1:8080",
  "data_dir": "~/.mcpproxy",
  "api_key": "your-secret-api-key",
  "enable_socket": true,
  "health_check_interval": "30s",
  "tool_discovery_interval": "5m",
  "tools_limit": 15,
  "tool_response_limit": 20000,
  "enable_code_execution": false,
  "code_execution_timeout_ms": 120000,
  "code_execution_max_tool_calls": 0,
  "code_execution_pool_size": 10,
  "features": {
    "enable_web_ui": true
  },
  "mcpServers": []
}

Options

Server Settings

Option	Type	Default	Description
listen	string	127.0.0.1:8080	Address and port to listen on
data_dir	string	~/.mcpproxy	Directory for data storage
api_key	string	auto-generated	API key for REST API authentication
enable_socket	boolean	true	Enable Unix socket/named pipe for local communication

Feature Flags

Option	Type	Default	Description
features.enable_web_ui	boolean	true	Enable the web management interface

Tool Discovery Settings

Option	Type	Default	Description
tools_limit	integer	15	Maximum tools to return in a single request
tool_response_limit	integer	20000	Maximum characters in tool response

Tool Discovery & Health Check Intervals

MCPProxy keeps upstream connections fresh with two independent background loops:

• a lightweight liveness probe that sends a standard MCP ping to confirm the connection is alive, and
• a periodic tool-discovery sweep that re-lists tools to rebuild the search index. (Tool changes are also picked up reactively via notifications/tools/list_changed; the sweep is a fallback for servers that don't advertise listChanged.)

Both cadences are configurable globally, and can be overridden per server (see Upstream Servers). Values are duration strings such as 30s, 5m, or 1h.

Option	Type	Default	Description
health_check_interval	duration	30s	Cadence of the lightweight liveness ping. Accepts 0s or 5s–1h. 0s disables the probe.
tool_discovery_interval	duration	5m	Cadence of the periodic tools/list re-index sweep. Accepts 0s or 30s–24h. 0s disables the sweep.

Resolution order: per-server value → global value → built-in default. Leaving a key unset preserves the previous behaviour, so existing configs are unaffected by an upgrade.

{
  "health_check_interval": "30s",
  "tool_discovery_interval": "5m",
  "mcpServers": [
    {
      "name": "chatty-server",
      "health_check_interval": "2m",
      "tool_discovery_interval": "0s"
    }
  ]
}

Notes:

• 0s = disabled. Disabling the discovery sweep for a server that does not support listChanged means tool changes are only picked up on (re)connect — fine for static servers, worth knowing for dynamic ones. With the liveness probe disabled, a dead transport is detected lazily (on the next real tool call or discovery sweep) rather than proactively.
• Docker-isolated servers: health_check_interval is a no-op — their liveness is monitored at the container level, not via MCP ping. tool_discovery_interval still applies. Remote (HTTP/SSE) servers benefit most from the ping-based probe.
• Hot reload: interval changes take effect on the next cycle without a full restart.
• These intervals are also editable in the Web UI and macOS app under Settings → Advanced → Tool discovery & health checks.

Code Execution Settings

Option	Type	Default	Description
enable_code_execution	boolean	false	Enable JavaScript code execution tool
code_execution_timeout_ms	integer	120000	Execution timeout in milliseconds
code_execution_max_tool_calls	integer	0	Maximum tool calls (0 = unlimited)
code_execution_pool_size	integer	10	VM pool size for code execution

MCP Servers

See Upstream Servers for detailed server configuration.

Hot Reload

MCPProxy watches the configuration file for changes and automatically reloads when modifications are detected. No restart is required for most configuration changes.

Environment Variable Overrides

Configuration options can be overridden using environment variables. See Environment Variables for details.