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fastmcp.server.tasks.elicitation

Background task elicitation support (SEP-1686). This module provides elicitation capabilities for background tasks running in Docket workers. Unlike regular MCP requests, background tasks don’t have an active request context, so elicitation requires special handling:
  1. Set task status to “input_required” via Redis
  2. Send notifications/tasks/status with elicitation metadata
  3. Wait for client to send input via tasks/sendInput
  4. Resume task execution with the provided input
This uses the public MCP SDK APIs where possible, with minimal use of internal APIs for background task coordination.

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Functions

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elicit_for_task 

elicit_for_task(task_id: str, session: ServerSession | None, message: str, schema: dict[str, Any], fastmcp: FastMCP) -> mcp.types.ElicitResult
Send an elicitation request from a background task. This function handles the complexity of eliciting user input when running in a Docket worker context where there’s no active MCP request. Args:
  • task_id: The background task ID
  • session: The MCP ServerSession for this task
  • message: The message to display to the user
  • schema: The JSON schema for the expected response
  • fastmcp: The FastMCP server instance
Returns:
  • ElicitResult containing the user’s response
Raises:
  • RuntimeError: If Docket is not available
  • McpError: If the elicitation request fails

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relay_elicitation 

relay_elicitation(session: ServerSession, session_id: str, task_id: str, elicitation: dict[str, Any], fastmcp: FastMCP) -> None
Relay elicitation from a background task worker to the client. Called by the notification subscriber when it detects an input_required notification with elicitation metadata. Sends a standard elicitation/create request to the client session, then uses handle_task_input() to push the response to Redis so the blocked worker can resume. Args:
  • session: MCP ServerSession
  • session_id: Session identifier
  • task_id: Background task ID
  • elicitation: Elicitation metadata (message, requestedSchema)
  • fastmcp: FastMCP server instance

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handle_task_input 

handle_task_input(task_id: str, session_id: str, action: str, content: dict[str, Any] | None, fastmcp: FastMCP) -> bool
Handle input sent to a background task via tasks/sendInput. This is called when a client sends input in response to an elicitation request from a background task. Args:
  • task_id: The background task ID
  • session_id: The MCP session ID
  • action: The elicitation action (“accept”, “decline”, “cancel”)
  • content: The response content (for “accept” action)
  • fastmcp: The FastMCP server instance
Returns:
  • True if the input was successfully stored, False otherwise