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MCP client setup

Start the Prism MCP server, then point your client (Claude Code, Claude Desktop, Cursor, VS Code Copilot, …) at it.

Automated setup

Run prism setup to register Prism MCP in Claude Code, Codex CLI, OpenCode, and Hermes Agent automatically — no manual file editing needed. The sections below cover the manual approach for clients not yet supported by prism setup (Claude Desktop, Cursor, VS Code Copilot).

Start Prism

prism serve

Prism ready at http://localhost:3000/mcp | workspace: off

Leave the terminal open — the server runs in the foreground. Stop with Ctrl+C.

The default URL is http://localhost:3000/mcp. Every client example below assumes that URL; adjust the host/port if you ran prism serve --port 4000.

Clients

Edit .claude/settings.json (in your project, or in %USERPROFILE% for a global config on Windows):

{
  "mcpServers": {
    "prism": {
      "url": "http://localhost:3000/mcp"
    }
  }
}

Claude Code connects over HTTP to the running server — you start Prism manually, Claude Code doesn't launch it.

Edit claude_desktop_config.json, located at %APPDATA%\Claude\claude_desktop_config.json:

{
  "mcpServers": {
    "prism": {
      "command": "prism",
      "args": ["serve"]
    }
  }
}

Claude Desktop will launch prism serve as a child process when it starts, and stop it when it exits. Works because prism.exe is on the system PATH after the installer.

Edit .cursor/mcp.json (workspace) or ~/.cursor/mcp.json (global):

{
  "mcpServers": {
    "prism": {
      "url": "http://localhost:3000/mcp"
    }
  }
}

Same pattern as Claude Code — start prism serve yourself.

Add to .vscode/mcp.json:

{
  "servers": {
    "prism": {
      "type": "http",
      "url": "http://localhost:3000/mcp"
    }
  }
}

The server must be running before Copilot connects.

Enabling the interactive debugger

Debug tools are registered only when IRIS_DEBUG_ENABLED=true. Start Prism with that env var set if you want Claude (or any other client) to have access to debug_start, debug_step, etc.:

$env:IRIS_DEBUG_ENABLED = "true"
prism serve

See Interactive debugger for the full workflow.

Enabling workspace mode

Workspace mode unlocks two additional MCP tools (put_document, put_and_compile) that read files from a local directory. Set IRIS_WORKSPACE to the path you want the AI to push code from:

$env:IRIS_WORKSPACE = "C:\work\myapp\src"
prism serve

Without it, the tools are not registered (and the startup log shows workspace: off).

Verifying the connection

Ask your client to call get_server_info — a zero-argument tool that returns the IRIS version. Any response means the transport is wired up correctly. If the AI says the tool isn't available, re-check the client config file's path and JSON validity.