# arc mcp

Arc agent documentation

Run Arc as an MCP server over stdio

[CLI reference index](/arc/docs/reference/cli) · [CLI behavior guide](/arc/docs/guides/cli)

## arc mcp

Run Arc as an MCP server over stdio

```text
usage: arc mcp [-h] [--agent AGENT] [--base-url BASE_URL] [--no-ensure]
               [--storage STORAGE] [--ensure-timeout ENSURE_TIMEOUT]
               [--resume-key RESUME_KEY] [--progressive-tools] [--full-tools]

options:
  -h, --help            show this help message and exit
  --agent AGENT         Agent ID to register as
  --base-url BASE_URL
  --no-ensure           Skip auto-ensure; assume the daemon is already
                        running.
  --storage STORAGE     Storage path used by auto-ensure. Defaults to <arc
                        data-root>/app.db.
  --ensure-timeout ENSURE_TIMEOUT
                        Seconds auto-ensure waits for the daemon to come up.
  --resume-key RESUME_KEY
                        Local adapter identity slot. After arc_join, a
                        restarted MCP bridge resumes that exact joined
                        identity instead of silently falling back to --agent.
                        Intended for app-global adapters.
  --progressive-tools   Progressive disclosure: advertise only the meta-tools
                        (arc_search_tools / arc_describe_tool / arc_call_tool)
                        plus a couple live-loop essentials, instead of the
                        full tool list. Shrinks the MCP tool-definition
                        context for small / local models; the full tool set
                        stays reachable via arc_call_tool. Without either
                        flag, the daemon's per-harness setting decides (GET
                        /v1/tool-surface).
  --full-tools          Force the full tool list, overriding the daemon's per-
                        harness tool-surface setting.

```

### Argument defaults

| Argument | Required | Default | Choices |
| --- | --- | --- | --- |
| `--agent` | no | "mcp-client" | — |
| `--base-url` | no | "http://127.0.0.1:6969" | — |
| `--no-ensure` | no | false | — |
| `--storage` | no | null | — |
| `--ensure-timeout` | no | 30.0 | — |
| `--resume-key` | no | null | — |
| `--progressive-tools` | no | false | — |
| `--full-tools` | no | false | — |