MCP Client

View as Markdown

A RocketRide tool node that connects to an external Model Context Protocol server and exposes its tools to AI agents.

What it does

Connects to an MCP server over one of three transports (STDIO (local subprocess), Streamable HTTP, or legacy HTTP+SSE), performs the MCP initialize handshake, discovers the server's tools via tools/list when the pipeline starts, and exposes them to agent nodes. Agents then discover and invoke these tools during their reasoning loop; each call is forwarded to the server as tools/call and the raw MCP result is returned.

This node has no pipeline lanes: it is a control-plane tool node, connected to agents via the tools invoke channel.

Tools are namespaced as serverName.toolName (e.g. mcp.search_docs), where serverName is set in configuration. Tools are discovered once at pipeline startup and cached; a server that adds tools later requires a pipeline restart to pick them up.

The implementation is pure Python standard library (subprocess, urllib, JSON-RPC 2.0), no MCP SDK dependency and no extra packages to install. Each request has a 20-second timeout.

---

Configuration

Field	Type	Description
serverName	string	Default "mcp". Namespace prefix for tools: . (example: local.echo)
transport	string	Default "streamable-http". How to connect to the MCP server
commandLine	string	Default "python -m rocketride_mcp". Command line to launch MCP server (stdio transport). Example: python -m rocketride_mcp
endpoint	string	Default empty. MCP Streamable HTTP endpoint URL. Example: http(s)://host:port/mcp
sse_endpoint	string	Default empty. Legacy MCP SSE URL (old transport). Example: http://127.0.0.1:8000/sse
headers	object	Default {}. Extra HTTP headers for streamable-http/sse transports
bearer	string	Default empty. Optional Authorization bearer token

STDIO transport

Launches a local subprocess as the MCP server and speaks JSON-RPC over its stdin/stdout. The subprocess inherits the engine's environment (with PYTHONUNBUFFERED=1 set).

Field	Type / Default	Description
commandLine	string, default python -m rocketride_mcp	Command line to launch the MCP server. Parsed with shell-style quoting.

Older configs that used separate command + args fields are still accepted for backwards compatibility.

Streamable HTTP transport

Connects to a modern Streamable HTTP MCP endpoint (spec 2025-03-26 transport). Handles both plain-JSON and SSE-streamed responses, tracks the Mcp-Session-Id returned by the server, and sends a best-effort DELETE to terminate the session when the pipeline stops.

Field	Type / Default	Description
endpoint	string, default empty	MCP Streamable HTTP endpoint URL. Example: http(s)://host:port/mcp
headers	object, default {}	Extra HTTP headers
bearer	string, optional, secure	Optional Authorization bearer token

Legacy HTTP+SSE transport

Connects to an older two-channel MCP server: a long-lived SSE GET stream for responses (read on a background thread) plus an endpoint event that supplies the session-specific POST URL for requests.

Field	Type / Default	Description
sse_endpoint	string, default empty	Legacy MCP SSE URL. Example: http://127.0.0.1:8000/sse
headers	object, default {}	Extra HTTP headers
bearer	string, optional, secure	Optional Authorization bearer token

Configuration is validated at save time: commandLine is required for stdio, endpoint for streamable-http, and sse_endpoint for sse.

---

Profiles

Profile	Transport	Notes
RocketRide MCP server (stdio) (default)	stdio	Launches python -m rocketride_mcp
Generic MCP server (Streamable HTTP)	streamable-http	Enter endpoint URL
Generic MCP server (legacy HTTP+SSE)	sse	Enter SSE endpoint URL

---

Authentication

For the HTTP transports (streamable-http and sse), set bearer to send an Authorization: Bearer <token> header on every request. The token is stored encrypted and masked in the UI. Arbitrary additional headers (e.g. API-key headers) can be supplied via headers; a bearer value overrides any Authorization key in headers.

The STDIO transport has no authentication fields: the subprocess runs locally with the engine's environment.

---

Butterbase preset

services.butterbase.json in this directory defines Butterbase MCP Client, a branded preset that reuses this node's implementation (not a separate node). It pins the transport to streamable-http with endpoint https://api.butterbase.ai/mcp, namespaces tools as butterbase.<tool> (e.g. butterbase.init_app), and surfaces the bearer field as a Butterbase API key (bb_sk_..., created in the Butterbase dashboard). Prerequisite: enable Developer Mode on your Butterbase app so the agent can create and modify resources.

---

Notes

• Protocol versions advertised during initialize: 2024-11-05 for STDIO, 2025-11-25 for Streamable HTTP and SSE.
• Tool calls must use the fully namespaced server.tool form; a call addressed to a different serverName than this node's is rejected.
• The MCP server process/connection is started in beginGlobal and shut down in endGlobal; a failed handshake or tool discovery fails pipeline startup with a warning.

---

Upstream docs

• Model Context Protocol specification

---

Schema

Butterbase MCP Client (services.butterbase.json)

Field	Type	Description	Default
mcp_client.bearer	string	API Key Butterbase API key (bb_sk_...). Create one in the Butterbase dashboard: dashboard.butterbase.ai → API Keys. Sent as an Authorization Bearer token.	""
mcp_client.endpoint	string	Endpoint Butterbase MCP Streamable HTTP endpoint. Defaults to the production server.	"https://api.butterbase.ai/mcp"
mcp_client.serverName	string	Server name Namespace prefix for the discovered tools: . (example: butterbase.init_app).	"butterbase"

MCP Client (services.json)

Field	Type	Description	Default
mcp_client.bearer	string	Bearer token Optional Authorization bearer token	""
mcp_client.commandLine	string	Command line Command line to launch MCP server (stdio transport). Example: python -m rocketride_mcp	"python -m rocketride_mcp"
mcp_client.endpoint	string	Endpoint MCP Streamable HTTP endpoint URL. Example: http(s)://host:port/mcp	""
mcp_client.headers	object	Headers Extra HTTP headers for streamable-http/sse transports	{}
mcp_client.serverName	string	Server name Namespace prefix for tools: . (example: local.echo)	"mcp"
mcp_client.sse_endpoint	string	SSE endpoint (legacy) Legacy MCP SSE URL (old transport). Example: http://127.0.0.1:8000/sse	""
mcp_client.transport	string	Transport How to connect to the MCP server	"streamable-http"