Antigravity

Last verified: 2026-07-21

As of July 2026, Antigravity still can't complete the sign-in for a third-party remote MCP server like ours natively — Google documents the limitation, and it's tracked as an open bug (antigravity-cli issue #25: the client reads the server's metadata but never contacts its authorization server). The steps below use a community local-bridge workaround instead.

Prerequisites

A Manyreach account + your API key (Manyreach web app → API & Integrations)
Antigravity installed (the 2.x app/IDE, or the 1.x CLI — ideally the latest build), signed in with a Google account
Node.js 18+ available on your machine (so npx works) — needed for the bridge below

Steps

Adding the server URL directly looks like it works, but every tool call then fails — Antigravity never completes the sign-in for third-party servers (the open bug above). So instead, register a small local bridge that handles the sign-in itself and gives Antigravity a plain local command to run:

Open Manage MCP Servers → View raw config (via the … menu in the Agent Panel, or Settings → Customizations in the 2.x app) to edit mcp_config.json directly — the global file is ~/.gemini/config/mcp_config.json, a per-workspace one is .agents/mcp_config.json, and in the CLI you can type /mcp for the interactive manager.
Add:
```
{
  "mcpServers": {
    "manyreach": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://mcp.manyreach.com/mcp"]
    }
  }
}
```
This uses mcp-remote, a community package that handles the sign-in on your machine and passes the connection through to Antigravity — it isn't an Antigravity or Manyreach feature, and we haven't certified it beyond confirming it's the pattern others use for this same limitation. (Optionally append "--transport", "http-only" to the args — our server speaks Streamable HTTP, so this skips the bridge's fallback probing.)
Save, then click Refresh under Installed MCP Servers. Fully restart Antigravity if the server still doesn't appear.
The first time a tool from manyreach is used, mcp-remote opens a browser window on its own to run the authorization.

What the authorization looks like

Your browser opens a Manyreach authorization page. Paste your API key there and click Authorize. The key is checked once and never shown to the AI — afterwards the connection stays signed in on its own. The window is opened by the bridge rather than a screen inside Antigravity itself, but it's the same authorization page either way.

Verify

Ask Antigravity's agent to "describe the Manyreach catalog". It should call the describe tool and list resources like campaign, prospect, and sender.

Troubleshooting

Added it as a plain URL (no bridge) — it shows connected, or offers an Authenticate button, but every tool call 401s — that's the known limitation above (antigravity-cli #25); use the mcp-remote bridge instead, there's no direct fix today.
New server doesn't appear — click Refresh under Installed MCP Servers, or fully restart Antigravity.
Can't find the config file, or edits don't seem to apply — always open it via Manage MCP Servers → View raw config rather than a remembered path; the location has drifted across versions (and a workspace .agents/mcp_config.json can shadow the global file).
Authorized in the IDE, but the CLI still asks (or vice versa) — the CLI keeps its own token store that doesn't sync with the IDE; authorize in the client you actually use.
Tool results come back missing content on the CLI — update to CLI 1.1.5 or newer; older builds silently dropped embedded resources in tool results (our documentation pages are exactly that).
Status indicator stays grey or red even though it's working — still reported as unreliable; try a tool call before assuming the connection is broken (a call that used to hang forever now errors out after a timeout instead).