Antigravity Delegate MCP

A distributable local-STDIO MCP server that lets Codex invoke Antigravity CLI from any project. The global server is policy-neutral; each project owns its routing guidance and enforceable policy.

Install from a release package

Clone the public repository:

git clone --depth 1 https://github.com/silennsong/Antigravity-MCP-Tool.git
cd Antigravity-MCP-Tool
python3 bootstrap.py --install-agy

Or download and extract the source archive from the latest GitHub Release, inspect bootstrap.py, then run:

python3 bootstrap.py --install-agy

The bootstrapper:

1. Creates an isolated venv under ~/.local/share/antigravity-delegate-mcp/venv.

2. Installs this package without modifying the system Python environment.

3. Optionally installs agy from Google's official installer.

4. Registers antigravity_delegate globally through codex mcp add.

5. Preserves unrelated Codex configuration and adds MCP timeout/tool settings.

6. Runs doctor.

For interactive onboarding as part of setup:

python3 bootstrap.py --install-agy --auth --configure-models

Google OAuth, terms, data-use choices, and workspace trust require the user to interact with Antigravity. The installer does not silently accept them.

See AGENT_INSTALL.md for a prompt that can be copied to a local coding agent.

Project homepage: https://github.com/silennsong/Antigravity-MCP-Tool

Related MCP server: Grok Plugin Codex

Commands

antigravity-delegate-mcp install --replace
antigravity-delegate-mcp auth --workspace /path/to/project
antigravity-delegate-mcp configure-models
antigravity-delegate-mcp init-project --workspace /path/to/project --profile read-only
antigravity-delegate-mcp validate-policy --workspace /path/to/project
antigravity-delegate-mcp doctor --workspace /path/to/project
antigravity-delegate-mcp doctor --deep --workspace /path/to/project

init-project offers two profiles:

• read-only: generates routing rules, a restrictive project policy, a local JSON Schema, and maps the mode to agy --mode plan --sandbox --disable-slash-commands.

• open: creates a minimal project policy without global task/model/mode restrictions.

Existing AGENTS.md files are not overwritten. Use --force to append a marked Antigravity section after reviewing the file.

The read-only profile also adds scoped Antigravity CLI grants in ~/.gemini/antigravity-cli/settings.json: recursive read_file(<project>) is allowed and write_file(<project>) is denied. Use --no-agy-permissions to skip that change.

Responsibility split

Global layer:

• Registers one delegate_to_antigravity MCP tool.

• Resolves stored or environment-provided model names.

• Adapts to the verified agy print-mode flags.

• Applies process timeout/output handling and returns structured metadata.

• Does not globally hard-code task categories, model routing, or read/write behavior.

Project layer:

• AGENTS.md tells Codex when delegation is useful.

• .codex/antigravity-policy.json defines enforceable task, model, mode, prompt, CLI-argument, output, and environment rules.

• .codex/antigravity-policy.schema.json gives editors a local policy schema.

• The closest policy found while walking upward from workspace is used.

Without a project policy, the global MCP applies no semantic task restriction.

Authentication and model configuration

The official Antigravity CLI installer for macOS/Linux is:

curl -fsSL https://antigravity.google/cli/install.sh | bash

This project downloads the installer before executing it instead of piping it blindly. To complete Google OAuth and project trust:

antigravity-delegate-mcp auth --workspace /path/to/project

Then configure exact model IDs returned by agy models:

antigravity-delegate-mcp configure-models \
  --flash gemini-3.6-flash-low \
  --pro gemini-3.1-pro-high \
  --non-interactive

Mappings are stored with mode 0600 in:

~/.config/antigravity-delegate/config.json

Environment variables such as ANTIGRAVITY_FLASH_MODEL override stored mappings. Exact model input is also supported when project policy permits it.

Headless permissions

Antigravity print mode cannot display interactive tool-approval cards. A project that needs file access must first complete workspace trust or configure appropriately scoped Antigravity permission grants. init-project --profile read-only handles the scoped read/deny-write grant automatically. Do not solve this with --dangerously-skip-permissions unless the project explicitly chooses that risk.

The MCP treats exit code 0 with empty stdout as an error and returns Antigravity's permission explanation instead of reporting false success.

Tool input

{
  "task": "Inspect the repository entry points and map the main modules.",
  "task_kind": "repository_exploration",
  "workspace": "/absolute/path/to/current/project",
  "model_tier": "flash",
  "mode": "read_only",
  "max_output_chars": 12000,
  "timeout_seconds": 600
}

Globally, task_kind, model_tier, and mode accept project-defined strings. Project policy may restrict them. Passing model uses an exact Antigravity model name instead of tier lookup.

Project policy fields

• version

• allowed_task_kinds

• allowed_model_tiers

• allow_explicit_model

• allowed_modes

• model_tier_task_kinds

• mode_cli_args

• min_task_chars, max_task_chars

• max_output_chars, max_timeout_seconds

• forbidden_task_patterns

• worker_instructions

• required_output_sections

• forward_env

Use validate-policy or doctor before relying on a new policy.

Build distributable artifacts

python3 -m build

Outputs:

dist/antigravity_delegate_mcp-<version>-py3-none-any.whl
dist/antigravity_delegate_mcp-<version>.tar.gz

Verification

python3 -m unittest discover -s tests -v
antigravity-delegate-mcp doctor --deep --workspace /path/to/project
codex mcp get antigravity_delegate

Runtime Python dependencies are intentionally empty. Python 3.10 or newer is required.