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Choosing an agent

The side panel runs on an agent CLI you already have logged in. Three are supported, and switching is a click.

3 min read Edit this page on GitHub

This is only about the side panel. Driving Browsentic from another tool is MCP clients, and that direction is fully agent-agnostic.

Picking one

In the extension popup, or behind the side panel's status pill. Each is listed with its state — ready, not installed, needs setup — so a missing CLI is visible before you send an instruction rather than after.

The same thing from a terminal:

browsentic-mcp agent                  # what is installed, and what runs the side panel
browsentic-mcp agent codex            # switch
browsentic-mcp agent setup antigravity

Switching takes effect on the next instruction. It also drops the conversation being held open: agents cannot resume each other's sessions, so the next instruction starts a fresh one.

The three

Claude Code Codex Antigravity
Vendor Anthropic OpenAI Google
Binary claude codex agy
Install npm i -g @anthropic-ai/claude-code npm i -g @openai/codex antigravity.google/docs/cli/install
Default model claude-sonnet-5 the CLI's own the CLI's own
Effort names low…max minimal…high low…high
Kept off your machine by a per-run tool allowlist plus an explicit deny list --sandbox read-only its own permission rules

All three get the same system prompt, the same browsentic MCP server pointed back at the daemon, and the same approval gate. What differs is how well each one can be fenced off from the rest of your machine — see internals/guardrails.md § Spawn containment for exactly what each flag buys.

Keep whichever you use reasonably current. Browsentic passes flags that contain the run. A build too old to understand them fails the run with an explicit "update it" message rather than running uncontained.

Antigravity needs one permission rule

Headless agy soft-denies any MCP tool it has no rule for, which would refuse every browser action. The popup shows this as needs setup.

Pressing the button — or browsentic-mcp agent setup antigravity — appends exactly one entry, mcp(browsentic/*), to permissions.allow in ~/.gemini/antigravity-cli/settings.json, leaving the rest of that file alone. Nothing is written until you press it. If you have a deny rule covering the same tools, Browsentic will not overrule it — remove it yourself.

Per-agent settings

In ~/.browsentic/config.json:

{
  "agent": "claude",
  "agents": {
    "claude": { "bin": "/opt/homebrew/bin/claude", "model": "claude-sonnet-5", "effort": "high" },
    "codex": { "bin": "codex", "model": "gpt-5.6-terra" },
    "antigravity": { "bin": "agy" }
  }
}
Key Default Effect
agent claude Which CLI the side panel runs on. The agent picker writes this.
agents.<name>.bin the CLI's own command name Absolute path to the binary. Set this when the daemon's PATH differs from your shell's — the usual cause of AGENT_MISSING.
agents.<name>.model claude-sonnet-5 for Claude, otherwise the CLI's own default Passed as --model.
agents.<name>.effort unset Passed as that CLI's reasoning-effort flag. A value the CLI does not accept is dropped rather than failing the run.

Changes apply to the next run — the config is re-read each time, no daemon restart needed.

The pre-0.2 top-level claudeBin, model and effort keys are still honoured, and read as the Claude runner's settings.

Common problems

Symptom Fix
AGENT_MISSING The daemon's PATH differs from your shell's. Set agents.<name>.bin to an absolute path.
AGENT_NEEDS_PERMISSION Antigravity has no rule for Browsentic's tools. Press the button, or browsentic-mcp agent setup antigravity.
Codex: "not logged in" The daemon inherits no session. Run codex login, then retry.
"does not understand the flags Browsentic uses" The CLI is too old. Update it.
Antigravity answers but never touches the page Its permission rule was removed. browsentic-mcp agent reports needs setup again.

See also