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MCP Servers

The MCP node connects your agent to a Model Context Protocol server, exposing its tools to the LLM. The agent can call these tools during a conversation to fetch data, run actions, or interact with external systems.

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Adding an MCP node

  1. Drag the MCP node from the sidebar (Integration category) onto the canvas
  2. Connect its output handle to the Framework node’s tools_in handle
  3. Configure the node parameters

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Parameters

ParameterTypeRequiredDescription
serverUrlstring✅The MCP server’s HTTP endpoint URL
authTypeenum—Authentication type: none, bearer, or api_key
authValuestring—The token or API key value (if auth is enabled)
selectedToolstool_selector—Which tools from the server to expose to the LLM

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Discovering tools

After entering a serverUrl, click Load Tools in the Properties Panel. Voiceblox calls /api/mcp-tools to fetch the tool list from the server. You’ll see each tool’s name and description. Check the tools you want to expose.

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How it works at runtime

When the agent is running and the LLM decides to call a tool:
  1. The agent connects to the MCP server via StreamableHTTPClientTransport
  2. It calls callTool() with the tool name and arguments
  3. The result is streamed back to the LLM as tool output
  4. The agent publishes a tool_call event (visible in step highlighting)

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Authentication

For servers that require authentication:
  • Bearer token: Set authType to bearer and paste your token in authValue. The server receives Authorization: Bearer {token}.
  • API key: Set authType to api_key and paste your key in authValue. The server receives x-api-key: {key}.

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Multiple MCP servers

You can connect multiple MCP nodes to the same Framework node via the tools_in handle (unlimited connections). The agent will have access to all selected tools from all connected servers.