Request params reference

Field	Type	Default
`task`	`mcp.types.TaskMetadata \| None`	`None`
`meta`	`mcp.types.RequestParams.Meta \| None`	`None`
`messages`	`list`	`[]`
`modelPreferences`	`mcp.types.ModelPreferences \| None`	`None`
`systemPrompt`	`str \| None`	`None`
`includeContext`	`Optional`	`None`
`temperature`	`float \| None`	`None`
`maxTokens`	`int`	`2048`
`stopSequences`	`list[str] \| None`	`None`
`metadata`	`dict[str, typing.Any] \| None`	`None`
`tools`	`list[mcp.types.Tool] \| None`	`None`
`toolChoice`	`mcp.types.ToolChoice \| None`	`None`
`model`	`str \| None`	`None`
`use_history`	`bool`	`True`
`max_iterations`	`int`	`99`
`parallel_tool_calls`	`bool`	`True`
`response_format`	`typing.Any \| None`	`None`
`template_vars`	`dict`	`PydanticUndefined`
`mcp_metadata`	`dict[str, typing.Any] \| None`	`None`
`tool_execution_handler`	`typing.Any \| None`	`None`
`emit_loop_progress`	`bool`	`False`
`streaming_timeout`	`float \| None`	`300.0`