Bedrock AgentCore > Structures > HarnessToolUseBlockStart HarnessToolUseBlockStart¶ Structure Class¶ HarnessToolUseBlockStart dataclass ¶ Start payload for a tool use content block. Attributes¶ name instance-attribute ¶ name: str The name of the tool being called. server_name class-attribute instance-attribute ¶ server_name: str | None = None The name of the MCP server providing this tool. tool_use_id instance-attribute ¶ tool_use_id: str The unique ID of this tool use. type class-attribute instance-attribute ¶ type: str | None = None The type of tool use.