Where does Antigravity look for MCP Servers?

In my previous post, I explored where Antigravity (AGY) looks for agent skills. In this post, I’ll briefly explore the same for Model Context Protocol (MCP) servers and mention the MCP server caching that’s worth knowing about.

MCP Configuration

AGY docs on MCP: https://antigravity.google/docs/mcp

Thankfully, MCP server configuration is more straightforward than skills. There are two places for MCP configuration:

Workspace: .agents/mcp_config.json
Global: ~/.gemini/config/mcp_config.json

This applies to all three flavours: AGY, AGY CLI, and AGY IDE.

MCP Server Caching

How to install MCP servers depends on the AGY flavour you’re using. I won’t cover MCP Server installation in detail here, you can check the docs for that.

In the end, you’ll have an entry in ~/.gemini/config/mcp_config.json (or .agents/mcp_config.json if you want to restrict MCP servers to a specific workspace manually).

Here’s an example for Cloud Run MCP Server:

{
  "mcpServers": {
    "cloudrun": {
      "command": "npx",
      "args": [
        "-y",
        "@google-cloud/cloud-run-mcp"
      ]
    }
  }
}

However, I want to mention about MCP server caching.

Once you have an MCP server installed, AGY, AGY IDE and AGY CLI cache it in various locations. For example, the Cloud Run MCP server is cached in these locations:

~/.gemini/antigravity/mcp/cloudrun
~/.gemini/antigravity-ide/mcp/cloudrun
~/.gemini/antigravity-cli/mcp/cloudrun

If you look into these folders, you’ll see a bunch of .json files. Each file corresponds to an MCP method:

$ ls ~/.gemini/antigravity/mcp/cloudrun/
create_project.json         deploy_local_folder.json    list_projects.json
deploy_container_image.json get_service_log.json        list_services.json
deploy_file_contents.json   get_service.json

Why is this important? You’d think that you can uninstall an MCP server by simply removing it from the mcp configuration file. But that’s not enough. I found that AGY and AGY IDE still think the MCP server is installed and shows it in the UI and try to use it, even though it can’t. AGY CLI, on the other hand, detects the missing MCP server more quickly.

For that reason, if you want to uninstall a global or workspace level MCP server, make sure you also remove its cached locations.

Summary

Here’s a summary of where AGY saves agent skills and MCP servers from my last two blog posts:

~/.gemini/
├── config/
│   ├── mcp_config.json            # Global MCP server configuration
│   └── skills/                    # Global agent skills
├── antigravity/
│   ├── builtin/skills/            # Built-in skills (AGY)
│   └── mcp/                       # Cached MCP servers (AGY)
├── antigravity-cli/
│   ├── builtin/skills/            # Built-in skills (AGY CLI)
│   └── mcp/                       # Cached MCP servers (AGY CLI)
└── antigravity-ide/
    └── mcp/                       # Cached MCP servers (AGY IDE)

<workspace-root>/
└── .agents/
    ├── mcp_config.json            # Workspace-specific MCP server configuration
    └── skills/                    # Workspace-specific agent skills

MCP Configuration

MCP Server Caching

Summary

See also