Proposal: Explicitly supporting Long Running Tool Calls at protocol level

[contextablemark]

This discussion is to brainstorm approaches, get community input, and track progress on designing support for long running or delayed tool calls in AG-UI.

As referenced in Issue #170, we need to explore and develop a proposal for supporting long running tool calls at the protocol level.

Context

The current AG-UI protocol needs enhancement to more explicitly support scenarios where:

• Tool calls may take significant time to complete
• Results may be delivered asynchronously through delayed responses
• User interfaces need to handle pending/in-progress states appropriately

Goals

• Brainstorm different architectural approaches
• Gather community feedback on proposed solutions
• Define clear requirements and use cases
• Develop a comprehensive proposal for implementation

How to Participate

Interested parties should:

• Follow and comment in this Discussion for ongoing conversation
• Share relevant use cases and requirements
• Provide feedback on proposed approaches

[contextablemark]

Current state (as I see it) :

• Front end tool calls are already implicitly long running (i.e., based on current examples of HITL in the Dojo), so this should likely continue to be the default.
• Support for differentiating between long running and non-long running tool calls in agent frameworks is currently limited (i.e., it may just be ADK only - see Function Tool and Long Running Function Tool.)
• Given this, any additions to the protocol should likely be optional.

[NathanTarbert]

Thank you @contextablemark- would love to go over this at the next working group meeting.

[contextablemark]

Initial Proposal :

Extend the Tool definition, by adding a "longRunning" attribute :

interface Tool {
  name: string // Unique identifier for the tool
  description: string // Human-readable explanation of what the tool does
  longRunning: boolean // Indicates that the tool is long running (e.g., HITL). Defaults to true
  parameters: {
    // JSON Schema defining the tool's parameters
    type: "object"
    properties: {
      // Tool-specific parameters
    }
    required: string[] // Array of required parameter names
  }
}

The handling of this attribute would be at the discretion of the agent (i.e., it could simply be ignored if the agent handles all tools the same whether or not they are long running).