ACP Devtools CLI

A transparent stdio proxy between your editor and an ACP coding agent that captures every JSON-RPC frame, stores sessions in SQLite, and streams them to a local web inspector. See every request, response, and notification on a clickable timeline; replay or diff old sessions; validate captures against the official ACP schema; query the store from Claude Code over MCP.

What's inside

The acp-devtools binary is one CLI with subcommands plus a bundled UI:

• proxy — wraps any ACP agent and passes stdio through verbatim. Logs every frame to ~/.acp-devtools/captures.db and broadcasts to a local WebSocket on an ephemeral port; several editors run side by side without port conflicts.
• ui — web inspector at http://127.0.0.1:3737/. Vertical timeline, J/K navigation, Cmd+K palette, performance dashboard with p50/p99/max per method and auto-detected hotspots, request↔response pairing, spec-aware JSON tree, multi-day session waterfall.
• mcp — Model Context Protocol server (stdio) that exposes the capture store as eleven read-only tools: list_sessions, find_sessions_by_client, get_session_metadata, get_latency_stats, get_session_summary, get_session_messages, get_message, get_paired, search_messages, find_spec_violations, diff_sessions.
• replay — re-emits any saved session over the same WebSocket so the inspector treats it as if it were live.
• diff / inspect / stats / search / session-info / validate / export / import / mock-agent / mock-editor — headless workflows for terminals and CI.

Works with Zed, WebStorm, IntelliJ, PyCharm, Neovim, and Visual Studio via ReSharper — any editor that supports custom ACP servers — and with Claude Code, Codex, Goose, OpenCode, and 40+ other agents.

Install

npm install -g acp-devtools
which acp-devtools   # absolute path for editor configs that need it

Or run the UI without installing:

npx acp-devtools ui

Use it

Open the inspector:

acp-devtools ui
# → http://127.0.0.1:3737/  (browser auto-opens)

Add ACP Devtools to your editor as an agent server. The minimum Zed config (~/.config/zed/settings.json):

{
    "agent_servers": {
        "Claude Code (via ACP Devtools)": {
            "type": "custom",
            "command": "acp-devtools"
        }
    }
}

Pick your editor in the inspector's empty state and copy the pre-filled snippet (the absolute binary path is auto-resolved). Recipes for WebStorm / IntelliJ / PyCharm, Neovim, and Claude Code multi-profile setups are in the GitHub repo.

MCP server

acp-devtools mcp runs over stdio. Add it from the CLI:

claude mcp add acp-devtools -- acp-devtools mcp

Or check a project-scoped .mcp.json into the repo root:

{
    "mcpServers": {
        "acp-devtools": {
            "command": "acp-devtools",
            "args": ["mcp"]
        }
    }
}

After restarting Claude Code the eleven tools above become available (check /mcp). Every tool advertises readOnlyHint: true, idempotentHint: true, openWorldHint: false per the MCP annotations spec, and the server emits an instructions block on initialize so the connecting LLM knows where to start without scanning tools/list. Stdio only; no network surface; the server cannot write to captures.db.

Full documentation

Architecture, supported agents, JetBrains setup, Claude Code multi-profile recipes, troubleshooting, and the full CLI reference — all in the GitHub repo:

https://github.com/maksugr/acp-devtools

License

MIT