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The Builder is Opus’s visual workflow editor and preview environment. It provides a visual interface to drag-and-drop tasks, wire variable mappings, configure task parameters, and test execution with real-time feedback before activating workflows for production use.

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Overview

The Builder is where you design, configure, and test workflows before deploying them to production. Here you:
  • Create workflows by adding and connecting tasks in the visual Builder
  • Configure tasks with inputs, outputs, and task-specific parameters
  • Test with previews that simulate real execution with live state feedback
  • Set up integrations with external systems through Opus’s Integration Marketplace, or connect with any external API using the External Service task
    Opus’s Integration Marketplace supports 3,500+ integrations with over 36,000 different actions.
  • Validate before activation to catch errors early and reduce production issues
Think of the Builder as both your design tool and your testing environment. Investing time in thorough previews here pays dividends in fewer job failures later.

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Builder Fundamentals

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Tasks And Connections

Workflows are built from two simple elements:
ElementDescription
TasksIndividual steps that perform specific actions (AI processing, data import, human review, etc.)
ConnectionsLines between tasks that define how data flows and the order steps run
Each task has inputs (data it receives) and outputs (data it produces). When you connect two tasks, you’re passing data from one step to the next and telling the workflow which steps must finish before others can begin.

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Adding Tasks

Click the + button in the Builder or drag from the task palette to add tasks. Available task types include:
  • Opus Agent: Maximum capability agent that takes a natural language task description and intelligently figures out how to accomplish it
  • Custom Agent: Simple one-shot LLM interaction from popular providers (OpenAI, Anthropic, DeepSeek, etc.)
  • Opus Human Task: Assign tasks requiring human input
  • Decision Agent: Automated routing based on conditions defined via natural language or logical expressions
  • Human Decision Agent: Same as Decision Agent, but a human evaluates the conditions and makes the routing decision
  • Opus Code Expert: Execute custom Python code within your workflow
Quality assurance through human oversight or AI-powered validation.
  • Human Review: Pauses workflows for accept/reject decisions with optional editing—ideal for compliance checks and quality gates requiring human judgment.
  • Agentic Review: Uses AI to validate outputs against defined criteria, with optional auto-correction for scalable quality assurance without human bottlenecks.
Run another workflow as a sub-workflow, enabling modular workflow composition and reuse across your organization.
Connect to external services through Opus’s Integration Marketplace, which provides 3,500+ pre-built connectors with over 36,000 different actions for cloud storage, productivity tools, databases, CRMs, and more.
  • Import Data: Pull data from connected services (Google Drive, S3, etc.)
  • Export Data: Send results to external systems (Sheets, Slack, etc.)
  • Opus Text Extraction: Extract text from documents and images using OCR
  • External Service Intermediate: Connect to any external REST API via a variety of authentication options including Basic Auth, Bearer Auth, Header Auth, JWT, or No Auth.

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Connecting Tasks

To connect tasks:
  1. Click on an output port of the source task
  2. Drag to an input port of the destination task
  3. Release to create the edge
The Builder enforces valid connections—you cannot create circular dependencies or connect incompatible variable types.

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Task Configuration

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Variables

Each task defines typed input and output variables. For example: 
Input Variables:
  - document_text (Text): The content to process
  - max_length (Number): Maximum output length

Output Variables:
  - summary (Text): Generated summary
  - confidence (Number): Confidence score
When configuring a task, you can:
  • Link variables to upstream outputs (auto-populated from connected tasks)
  • Set static values for configuration parameters
  • Define new variables that downstream tasks can consume

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Builder Features

The Builder provides essential features for managing your workflow:

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Action Center

The Action Center is located at the top center of the Builder and displays all pending action items that must be resolved before you can run your workflow.
  • Shows issues like missing connections, unconfigured variables, and validation errors
  • The Auto-fix button lets Opus AI automatically resolve common configuration issues
  • When the Action Center shows “No action items,” your workflow is ready to test
Use Auto-fix liberally—it can save significant time by intelligently resolving configuration issues that would otherwise require manual intervention.
The auto-link feature uses AI to intelligently connect variables between tasks:
  • Available inside variable configuration panels and on the input panel for Opus Agent
  • Click the auto-link button to have Opus map matching inputs and outputs
  • Saves time when connecting multiple variables across complex workflows

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Clear Saved Data

The Builder caches data from completed runs to save costs and improve iteration speed. To perform a completely fresh run where all data is recalculated:
  • Click the Clear Saved Data button (located to the right of the Run Workflow button)
  • This clears all cached results from previous runs
  • Then click Run Workflow to execute all tasks from scratch

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Generate Variable

Opus supports a Generate Variable feature that creates mock data for your input variables:
  • Click the Generate Variable button in the Workflow Input task
  • Opus auto-generates sample values based on variable types and descriptions
  • Quickly test workflows without manually entering data

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Tidy Up

Click the Tidy Up button to automatically format and arrange your workflow tasks in a clean, organized layout. This feature:
  • Aligns tasks in a logical flow from left to right
  • Adjusts spacing for optimal readability
  • Organizes parallel branches neatly
This is especially helpful as workflows grow more complex or after making significant edits.

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Opus AI Assist

Opus AI Assist is the inline AI editing assistant that lets you modify your workflow using natural language. Located at the bottom left of the Builder, it allows you to describe changes in plain English and have Opus propose edits to your existing workflow. How to use:
1

Open Opus AI Assist

Click the Ask Opus AI Assist button at the bottom left of the Builder.
2

Describe your changes

Enter a description of the edits you want to make in the prompt field. For example:
  • “Add a Human Review task before the final email is sent”
  • “Route all high-risk outputs to a separate branch with a review”
  • “Change this agent to use a different model but keep the same inputs and outputs”
3

Review the proposal

Opus AI generates a Workflow Proposals plan showing the proposed changes to your workflow. Review the suggested edits in the modal.
4

Confirm or cancel

Click Confirm to apply the changes to your workflow, or close the modal to discard them.
What Opus AI Assist can do:
  • Add, delete, or move tasks
  • Rewire connections between tasks
  • Adjust variable mappings
  • Update task configurations
Changes are only applied after you review and confirm them in the Workflow Proposals modal. You stay in control of your workflow at all times.

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Running Workflows

The Builder includes a dedicated testing environment for running workflows with real-time feedback before activation.

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Executing A Test Run

1

Resolve action items

Check the Action Center and ensure all action items are resolved. Use Auto-fix to let Opus resolve them with AI, or fix them manually.
2

Provide test inputs

Enter values for all variables in the Workflow Input task. Use realistic data that represents expected production inputs, or use the Generate Variable feature to create mock data.
For file inputs, the maximum upload size is 10 MB per file.
3

Run the workflow

Click Run Workflow. The engine traverses your graph, executing tasks as their dependencies complete.
4

Observe execution

Watch as tasks transition through states:
  • Running: Currently executing (blue, animated)
  • Completed: Successfully finished (green)
  • Failed: Error occurred (red with message)
5

Review results

Click any task to inspect its outputs. Failed tasks show error details to help you debug.

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Caching And Clear Saved Data

To save costs and improve iteration speed, the Builder caches data from completed runs:
  • When you run the workflow again, tasks with unchanged inputs use cached results instead of re-executing
  • This allows rapid iteration without incurring full execution costs
To perform a completely fresh run where all data is recalculated:
  • Click the Clear Saved Data button (located to the right of the Run Workflow button)
  • Then click Run Workflow to execute all tasks from scratch

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Run Features

FeatureDescription
State animationsVisual feedback shows which tasks are active, waiting, or complete
Stop controlAbort long-running runs without getting stuck
Error surfacingTasks with errors are surfaced directly in the graph
Success bannerClear confirmation when run completes without errors
Result cachingCached data speeds up subsequent runs and reduces costs

Workflows

Understand workflow lifecycle, states, and best practices.

Jobs

Learn how workflows execute as auditable jobs.

Integrations

Explore all available integrations and setup guides.

Task Reference

Detailed documentation for each task type.