Connecting an MCP client

Choose a connection method and review the instance permissions first.

Connecting a client

1. Start Protohaund, activate a license and select a beta module.
2. Enable Enable for this instance in Settings → MCP Server → Agent access.
3. Set a clear Instance name, especially when several copies are running.
4. Select Transport → stdio in MCP Server → MCP Bridge → Agent connection, then copy Command and Arguments. If the bridge is already running with another transport, select Restart.
5. Add a local server to your MCP client: use the copied absolute command path, stdio transport and an empty argument list [].

The client launches the connector and exchanges messages over standard input/output. Opening the visible McpBridge window does not add a server to your client configuration. Protohaund does not configure external clients automatically.

Run the client and application as the same Windows user with the same privilege level. Each MCP client uses its own connection.

Connecting over HTTP

You can also use Streamable HTTP on the same computer:

1. Select Transport → Streamable HTTP in Settings → MCP Server → MCP Bridge → Agent connection.
2. Change Port if needed, then select Start or Restart.
3. Copy the URL and use Copy token to copy the access token.
4. Select Streamable HTTP in your MCP client and enter the URL and Bearer token. For clients configured with HTTP headers, use Authorization: Bearer <copied token>.

The default URL is http://127.0.0.1:52738/mcp. Connections from other computers are not supported. The bridge must be running before the client connects. Port and transport changes take effect when the bridge starts or restarts; reconnect your client afterwards. Only one transport is used at a time: starting HTTP closes existing stdio connections and rejects new ones. To return to stdio, select it and restart the bridge. If the port is in use, choose another one. For HTTP 401, check the client's access token. The current instance's permissions apply equally to both connection methods.

Troubleshooting

State	Check
Empty instances_list	Application running, valid license, access enabled, same Windows user
License required	Activation, overall license expiry and autonomous access in Account
PermissionDenied	Local permissions, active module and license rights
InstanceUnavailable	Discover instances again and select the current address
ContextChanged	Refresh state and action conditions; do not automatically repeat a change
IncompatibleVersion	Use McpBridge from a compatible distribution and reconnect the client

For startup errors, check MCP Bridge status and the technical log.