MCP Rubber Duck vs Memory (Knowledge Graph)

A side-by-side comparison of two AI, Data & Knowledge servers — tools, transport, auth, maintenance, and copy-paste config for each.

	MCP Rubber Duck Bridge to query multiple LLMs and CLI coding agents as AI "ducks" for diverse perspectives. Unverified stdio (local) API key TypeScript	Memory (Knowledge Graph) Official MCP server providing persistent, file-backed knowledge-graph memory across sessions. Verified stdio (local) No auth TypeScript
Category	AI, Data & Knowledge	AI, Data & Knowledge
Language	TypeScript	TypeScript
Transport	stdio (local)	stdio (local)
Auth	API key	None
GitHub stars	168	74k
Last commit	3 days ago	5 months ago
Verified
Actively maintained
Install	`npm install -g mcp-rubber-duck`	`npx -y @modelcontextprotocol/server-memory`
Repo	Open	Open

Verdict

Pick MCP Rubber Duck if you need the broadest set of tools.

Pick Memory (Knowledge Graph) if you want the official, vendor-maintained server, and you prefer the more popular, battle-tested option.

Add MCP Rubber Duck

Install / run

npm install -g mcp-rubber-duck

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "mcp-rubber-duck": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-rubber-duck"
      ],
      "env": {
        "MCP_SERVER": "true",
        "OPENAI_API_KEY": "sk-your-key-here",
        "DEFAULT_PROVIDER": "openai"
      }
    }
  }
}

Add Memory (Knowledge Graph)

Install / run

npx -y @modelcontextprotocol/server-memory

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "memory-knowledge-graph": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-memory"
      ],
      "env": {
        "MEMORY_FILE_PATH": "/absolute/path/to/memory.jsonl"
      }
    }
  }
}

FAQ

MCP Rubber Duck or Memory (Knowledge Graph) — which is better?

Pick MCP Rubber Duck if you need the broadest set of tools. Pick Memory (Knowledge Graph) if you want the official, vendor-maintained server, and you prefer the more popular, battle-tested option.

Can I use both MCP Rubber Duck and Memory (Knowledge Graph)?

Yes — MCP clients let you enable multiple servers at once. Add both configs to your client's mcpServers and use whichever tool fits the task.

Do MCP Rubber Duck and Memory (Knowledge Graph) work with Claude, Cursor and Windsurf?

Both do. Copy the per-client config below into Claude Desktop, Cursor, or Windsurf.

View MCP Rubber Duck →View Memory (Knowledge Graph) →More comparisons →