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Workflow tools let an agent call a deployed workflow endpoint variant during an agent run.

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Overview

Add a workflow tool when an agent should hand part of a task to an existing workflow. Fetch Hive starts the workflow as a normal workflow run, so it gets its own request ID, workflow run ID, workflow logs, and step trace. The parent agent also records the call as an agent tool span, with the workflow trace nested under that tool call in the agent run trace. Workflow tools use the selected workflow endpoint variant’s latest active version. The tool input schema is generated from the workflow’s start input declarations, so the model can pass the same top-level inputs that the workflow expects from an API call.

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How do I add a workflow tool?

  1. Open the parent agent in the agent editor.
  2. Click the add-tool button in the editor header.
  3. Choose a deployed workflow endpoint and variant from Workflow Tools.
  4. Enter the tool name and description the model should see.
  5. Save the tool.
The workflow endpoint and variant must belong to the same workspace as the agent. Tool names must be unique across the agent’s MCP tools, workflow tools, and sub agents.

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What gets logged?

Every workflow tool call creates two linked records:
  • A normal workflow run with its own request ID and workflow run ID.
  • A parent agent tool call with metadata that identifies the workflow tool and the child workflow run.
You can inspect the child workflow from workflow logs exactly like any other workflow invocation. In the agent trace, the parent tool span is named agent.tool.workflow, and the child workflow spans are attached below that span.

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When should I use workflow tools?

Use workflow tools when the delegated work is already modeled as a workflow, especially if it includes multiple deterministic steps, branching, integrations, or reusable workflow-specific logging. Use sub agents when the delegated work should be handled by another agent with its own instructions and tool set.