Highway MCP

The MCP front door for Highway Agents. It lets any MCP host (Claude Desktop/Code, opencode, Cursor, Claude mobile) drive durable, always-on agents that run server-side on the Highway Workflow Engine — the user runs no infrastructure, just an MCP client and a Highway API key.

It exposes three tools, each a thin wrapper over the Highway REST API:

The agent loop itself is the engine tool tools.agent.run_goal driven by the agent_run_goal workflow (one durable model turn per iteration, HITL approval before outbound actions). See the engine repo (enterprise/tools/agent.py, api/dsl_templates/agent_run_goal.py) and issue #749.

Prerequisites

• The Highway stack running and reachable (default http://localhost:7822).

• A Highway API key (hw_k1_...) with permissions submit_workflows, view_workflows, view_approvals, approve_workflows. Mint one via POST /api/v1/admin/api-keys (see engine docs).

Related MCP server: workflows-mcp

Run

pip install -e .

# stdio (for a local host like opencode/Claude Desktop)
HIGHWAY_BASE_URL=http://localhost:7822 HIGHWAY_API_KEY=hw_k1_xxx highway-mcp

# remote / streamable-http (reachable by laptop + mobile clients)
TRANSPORT=http PORT=8848 HIGHWAY_BASE_URL=https://highway.rodmena.app \
  HIGHWAY_API_KEY=hw_k1_xxx highway-mcp

Connect from opencode (dogfood)

Add to the host's MCP config (stdio example):

{
  "mcpServers": {
    "highway-agents": {
      "command": "highway-mcp",
      "env": {
        "HIGHWAY_BASE_URL": "http://localhost:7822",
        "HIGHWAY_API_KEY": "hw_k1_xxx"
      }
    }
  }
}

Then: run_goal("summarise what files are in /tmp") → the agent asks to run a shell command → get_status(<id>) shows a pending approval → approve(<key>) → the run resumes and completes; get_status returns the result.

Configuration

Status / follow-ups (Phase 0 spike)

• Auth is single-key from env. Production needs per-connection auth so each customer's own key (from the MCP session/OAuth) is forwarded — not one shared server key.

• Tool surface is a placeholder (shell_run → tools.shell.run, approval required). Validate the argument contract live and replace with the real connector tools (Gmail etc.) in Phase 1.

• Long-running calls already use the start→poll pattern (run_goal returns a handle; get_status polls). Progress-notification/resource streaming is a later nicety.

• Engine-side durability caveat for side-effecting tools: issue #750.