hermes-agent/website/docs/user-guide/features/acp.md

sidebar_position	title	description
11	ACP Editor Integration	Use Hermes Agent inside ACP-compatible editors such as VS Code, Zed, and JetBrains

ACP Editor Integration

Hermes Agent can run as an ACP server, letting ACP-compatible editors talk to Hermes over stdio and render:

• chat messages
• tool activity
• file diffs
• terminal commands
• approval prompts
• streamed thinking / response chunks

ACP is a good fit when you want Hermes to behave like an editor-native coding agent instead of a standalone CLI or messaging bot.

What Hermes exposes in ACP mode

Hermes runs with a curated hermes-acp toolset designed for editor workflows. It includes:

• file tools: read_file, write_file, patch, search_files
• terminal tools: terminal, process
• web/browser tools
• memory, todo, session search
• skills
• execute_code and delegate_task
• vision

It intentionally excludes things that do not fit typical editor UX, such as messaging delivery and cronjob management.

Installation

Install Hermes normally, then add the ACP extra from the install checkout:

cd ~/.hermes/hermes-agent && uv pip install -e '.[acp]'

This installs the agent-client-protocol dependency and enables:

• hermes acp
• hermes-acp
• python -m acp_adapter

Launching the ACP server

Any of the following starts Hermes in ACP mode:

hermes acp

hermes-acp

python -m acp_adapter

Hermes logs to stderr so stdout remains reserved for ACP JSON-RPC traffic.

For non-interactive checks:

hermes acp --version
hermes acp --check

Browser tools (optional)

Browser tools (browser_navigate, browser_click, etc.) depend on the agent-browser npm package and Chromium, which aren't part of the Python wheel. Install them with:

hermes acp --setup-browser           # interactive (prompts before ~400 MB download)
hermes acp --setup-browser --yes     # accept the download non-interactively

This is the standalone command. The terminal-auth flow (hermes acp --setup) also offers the browser bootstrap as a follow-up question after model selection, so most users never need to run --setup-browser directly.

What it does:

• Installs Node.js 22 LTS into ~/.hermes/node/ if missing
• npm install -g agent-browser @askjo/camofox-browser into that prefix (no sudo needed — npm's --prefix points at the user-writable Hermes-managed Node)
• Installs Playwright Chromium, or uses a detected system Chrome/Chromium when available

The bootstrap is idempotent — re-running it is fast and skips work that's already done.

Editor setup

VS Code

Install the ACP Client extension.

To connect:

1. Open the ACP Client panel from the Activity Bar.
2. Select Hermes Agent from the built-in agent list.
3. Connect and start chatting.

If you want to define Hermes manually, add it through VS Code settings under acp.agents:

{
  "acp.agents": {
    "Hermes Agent": {
      "command": "hermes",
      "args": ["acp"]
    }
  }
}

Zed

Configure Hermes as a custom agent server in Zed settings:

1. Open the Agent Panel.
2. Add a custom agent server with the following configuration:

{
  "agent_servers": {
    "hermes-agent": {
      "type": "custom",
      "command": "hermes",
      "args": ["acp"]
    }
  }
}

3. Start a new Hermes external-agent thread.

Prerequisites:

• Configure Hermes provider credentials first with hermes model, or set them in ~/.hermes/.env / ~/.hermes/config.yaml.

JetBrains

Use an ACP-compatible plugin and point it at hermes acp or hermes-acp.

Configuration and credentials

ACP mode uses the same Hermes configuration as the CLI:

• ~/.hermes/.env
• ~/.hermes/config.yaml
• ~/.hermes/skills/
• ~/.hermes/state.db

Provider resolution uses Hermes' normal runtime resolver, so ACP inherits the currently configured provider and credentials. Hermes also advertises a terminal auth method (--setup) for first-run ACP clients; this opens Hermes' interactive model/provider setup.

Host integration

These variables are set by an ACP host process (an editor or another agent harness) on the Hermes subprocess it spawns. They are not user configuration — do not set them by hand in .env or config.yaml.

Variable	Value	Effect
HERMES_ACP_SKIP_CONFIGURED_MCP	1	Skip starting the globally configured MCP servers from config.yaml before the ACP JSON-RPC loop begins.

Hermes normally starts every MCP server configured in config.yaml before it enters the ACP JSON-RPC loop. A host that owns MCP itself — passing the session's servers explicitly through session/new — does not need that global startup, and an unrelated slow or interactive MCP server would otherwise delay initialize. Setting the marker to exactly 1 lets such a host skip it.

Only the global config.yaml discovery is skipped. MCP servers supplied by the ACP session through session/new are still registered, so a host loses no capability it asked for. Any other value (unset, empty, 0, false) keeps the default behavior, so an unrelated truthy-looking string cannot silently disable MCP.

Session behavior

ACP sessions are tracked by the ACP adapter's in-memory session manager while the server is running.

Each session stores:

• session ID
• working directory
• selected model
• current conversation history
• cancel event

The underlying AIAgent still uses Hermes' normal persistence/logging paths, but ACP list/load/resume/fork are scoped to the currently running ACP server process.

Working directory behavior

ACP sessions bind the editor's cwd to the Hermes task ID so file and terminal tools run relative to the editor workspace, not the server process cwd.

Approvals

Dangerous terminal commands can be routed back to the editor as approval prompts. ACP approval options are simpler than the CLI flow:

• allow once
• allow always
• deny

On timeout or error, the approval bridge denies the request.

Session-scoped edit auto-approval

ACP exposes a third tier between allow once and allow always: Allow for session. Picking it from the editor's permission prompt records the approval inside the current ACP session only — every subsequent matching command in that session goes through without prompting, but a new ACP session (or restarting the editor) resets the slate and re-prompts the first time.

Option	Editor label	Scope	Persisted across restarts
allow_once	Allow once	This one tool call	No
allow_session	Allow for session	All matching calls in this ACP session	No — cleared when the session ends
allow_always	Allow always	All future sessions	Yes (written to the Hermes permanent allowlist)
deny	Deny	This one tool call	No

allow_session is the right default for an editor workflow where you trust an agent for the duration of a task but don't want to grant a long-lived allowlist entry. The safety trade-off is straightforward: the broader the scope, the less the editor will interrupt you, and the more damage a misbehaving agent (or prompt injection) can do before you notice. Start with allow_once for unfamiliar commands; promote to allow_session once you've seen the agent run the same pattern correctly a few times; reserve allow_always for truly idempotent commands you trust forever (e.g. git status).

The ACP bridge maps these options onto Hermes' internal approval semantics — allow_always writes a permanent allowlist entry the same way the CLI does, while allow_session only affects the in-process approval cache for the current ACP session.

Troubleshooting

ACP agent does not appear in the editor

Check:

• For manual/local development, verify the custom agent_servers command points to hermes acp.
• Hermes is installed and on your PATH.
• The ACP extra is installed (cd ~/.hermes/hermes-agent && uv pip install -e '.[acp]').

ACP starts but immediately errors

Try these checks:

hermes acp --version
hermes acp --check
hermes doctor
hermes status

Missing credentials

ACP mode uses Hermes' existing provider setup. Configure credentials with:

hermes model

or by editing ~/.hermes/.env. The terminal auth flow (hermes acp --setup) can also trigger the interactive provider/model setup.

See also

• ACP Internals
• Provider Runtime Resolution
• Tools Runtime