mcp-cassette

mcp-cassette is vcrpy for MCP. It records real MCP sessions between an agent (the client) and an MCP server into cassettes — structured, diffable, committable files — and later replays those cassettes as deterministic mock MCP servers, so agent test suites stop hitting live servers and stop being flaky, slow, and expensive.

{
  "mcpServers": {
    "mcp-cassette": {
      "command": "uvx",
      "args": [
        "mcp-cassette"
      ]
    }
  }
}

claude mcp add mcp-cassette uvx mcp-cassette

{
  "mcpServers": {
    "mcp-cassette": {
      "command": "uvx",
      "args": [
        "mcp-cassette"
      ]
    }
  }
}