Antigravity keeps refreshing and fails to load MCP tools

[kornelrabczak]

When configuring Archiledger as an MCP server in Antigravity (version 1.20.4-1), the client gets stuck in a constant refresh loop and fails to load the tools provided by the server.

As a result, the LLM running inside Antigravity cannot see or access the memory tools (e.g., create_entities, get_entity, read_graph, etc.), completely breaking the memory functionality.

Steps to Reproduce

Start Archiledger MCP server locally (e.g., on http://localhost:8080/mcp).
Configure Antigravity settings.json to connect to the server:

{
  "mcpServers": {
      "archiledger": {
          "serverUrl": "http://localhost:8080/mcp"
      }
  }
}

Open Antigravity v1.20.4-1.
Observe the tool initialization status, it gets stuck refreshing.
Ask the LLM to use memory tools, and observe that it reports having no access to them.

Expected Behavior

Antigravity should successfully connect to the Archiledger streamable HTTP endpoint, fetch the list of available tools, and make them available to the LLM context.

Possible Causes / Investigation Strategy

• Spring AI MCP implementation vs. Antigravity expectations: Check if the MCP JSON-RPC protocol implementation in Spring AI (currently using STREAMABLE) has any discrepancies or missing fields that Antigravity v1.20.4-1 specifically requires or chokes on.
• SSE Connection dropping: Determine if the Server-Sent Events (SSE) connection is dropping prematurely, forcing Antigravity to reconnect in a loop.
• Protocol versioning: Verify the MCP protocol version supported by the server vs the client.
• Tool schema validation: Check if any of the tool JSON schemas exported by the server are failing strict validation inside Antigravity (e.g., missing descriptions, unsupported property types).

[kornelrabczak]

response from antigravity backend:

{
    "states": [
        {
            "spec": {
                "serverName": "local-memory",
                "serverUrl": "http://127.0.0.1:8080/mcp"
            },
            "status": "MCP_SERVER_STATUS_PENDING"
        }
    ],
    "isLoading": true
}

[kornelrabczak]

Works fine with newest gemini-cli v0.32.0