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Computer Use Agent (CUA) - Implementation Plan

Status: Planning Priority: High Target: January 30, 2026 Vote with 👍

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Executive Summary

Build a Computer Use Agent (CUA) that wraps external MCP servers and enables AI-powered desktop control through natural language commands. The agent dynamically discovers tools from the external MCP server and registers them locally, using Lemonade (Qwen-Coder 30B) for intelligent reasoning about which actions to take. Goal: Let GAIA automate desktop features and system settings through natural language commands.

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Requirements

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Prerequisites

  • GAIA SDK v0.16+
  • Python 3.10+
  • Lemonade Server running with Qwen-Coder 30B
  • External MCP server for desktop control (user-provided)

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External MCP Server Requirements

External MCP servers must support the MCP Protocol:
  • One of: stdio or HTTP transport
  • initialize handshake
  • tools/list capability
  • tools/call for tool execution

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The Problem

GAIA agents currently cannot interact with desktop features and system settings. When agents need to:
  • Adjust system settings and preferences
  • Control hardware features and utilities
  • Query device status and capabilities
  • Automate repetitive system tasks
…they have no way to do so.
Current LimitationImpact
No desktop automationCan’t build end-to-end workflow agents
No system controlCan’t adjust settings or features
No device queriesCan’t check status or capabilities
Isolated from OSLimited to file/code operations only
Meanwhile, external MCP servers already provide desktop automation capabilities. GAIA just needs a way to connect to them.

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The Solution

A Computer Use Agent that connects to external MCP servers and exposes their tools to Lemonade: 
# Single command execution
python -m gaia.agents.cua.cli "turn on dark mode"

# List available tools from external server
python -m gaia.agents.cua.cli --list-tools

Desktop Automation

System settings, features, utilities Automate any supported function

Natural Language

Describe tasks in plain English AI figures out the steps

Tool-Agnostic

Works with any MCP server No hardcoded tool definitions

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Architecture

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Key Design Decisions

DecisionChoiceRationale
Base ClassAgent (not MCPAgent)CLI-first, no MCP server exposure needed
Connection Modesstdio + HTTPFlexibility for different external servers
Tool DiscoveryDynamic via tools/listNo hardcoded tool definitions
Error HandlingUser-friendly + verbose flagClean UX by default

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What This Agent Does NOT Do

  • Does NOT expose itself as an MCP server
  • Does NOT manage the external MCP server process
  • Future UI integration will use OpenAI-compatible API (out of scope)

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Components

ComponentPurposeImplementation
ComputerUseAgentMain agent classInherits from Agent, registers external tools
ExternalMCPClientProtocol handlerJSON-RPC 2.0 over stdio or HTTP
CLIUser interfaceSingle command execution, tool listing
Tool Registry BridgeTool integrationDynamically registers MCP tools with @tool system

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Data Flow

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Tool Execution Flow

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Connection Flow

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CLI Commands

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Execute Commands

# Single command (primary use case)
python -m gaia.agents.cua.cli "turn on dark mode"

# With verbose output
python -m gaia.agents.cua.cli "check my battery status" --verbose

# Silent mode (no step output)
python -m gaia.agents.cua.cli "enable power saver" --silent

# Show execution trace
python -m gaia.agents.cua.cli "what features does my laptop support" --trace

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Tool Discovery

# List available tools from external server
python -m gaia.agents.cua.cli --list-tools

# List tools with verbose connection info
python -m gaia.agents.cua.cli --list-tools --verbose

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Configuration Options

# Specify external MCP server URL
python -m gaia.agents.cua.cli --mcp-server-url http://localhost:9000 "enable dark mode"

# Use specific LLM model
python -m gaia.agents.cua.cli --model Qwen3-Coder-30B "check storage status"

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Configuration

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Environment Variables

VariableDefaultDescription
GAIA_CUA_MCP_URLstdioExternal MCP server URL or “stdio”

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Connection Modes

export GAIA_CUA_MCP_URL=stdio
python -m gaia.agents.cua.cli "turn on dark mode"

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Multi-Agent Future Architecture

The design supports future expansion with namespaced environment variables: 
GAIA_CUA_MCP_URL          # Computer Use Agent
GAIA_BROWSER_MCP_URL      # Future: Browser Agent
GAIA_FILESYSTEM_MCP_URL   # Future: File System Agent

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Implementation Plan

1

MCP Client Layer (TDD)

ExternalMCPClient class with stdio and HTTP transport, JSON-RPC 2.0 protocol, connection handling
2

Agent Implementation (TDD)

ComputerUseAgent inheriting from Agent, dynamic tool registration, Lemonade integration
3

Standalone CLI

Command parsing, single-command execution, --list-tools mode, error handling
4

Integration Tests

Real external server tests, Lemonade integration tests, connection mode tests
5

Documentation

User guide (docs/guides/cua.mdx), API reference, troubleshooting guide
6

Code Review & Coverage

Lint check, >90% test coverage, final review

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Project Structure

FilePurpose
agent.pyComputerUseAgent class
cli.pyStandalone CLI entry point
mcp_client.pyJSON-RPC client for external server
test_agent.pyUnit tests (mocked)
test_mcp_client.pyMCP client unit tests
test_connection_modes.pystdio vs HTTP mode tests
test_integration.pyReal server integration tests

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Success Metrics

MetricTarget
External server connection time (stdio)< 2 seconds
External server connection time (HTTP)< 500ms
Tool call latency overhead< 50ms
Supported connection modesstdio, HTTP
Test coverage> 90%
Graceful degradationAgent usable when server unavailable

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Comparison

FeatureDirect ImplementationCUA Agent
Desktop automationCustom integration codeUse any MCP server
Tool discoveryHardcoded definitionsDynamic via tools/list
LLM reasoningManual prompt engineeringLemonade handles it
Error handlingCustom per-toolStandardized, user-friendly
Future MCP serversRewrite everythingJust change URL

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Error Handling

The agent provides user-friendly error messages by default, with technical details available via --verbose: 
# Default: user-friendly message
$ python -m gaia.agents.cua.cli "turn on dark mode"
Error: External MCP server is not available.
Please ensure the server is running and try again.

# Verbose: includes technical details
$ python -m gaia.agents.cua.cli "turn on dark mode" --verbose
Error: External MCP server is not available.
Please ensure the server is running and try again.
Detail: Connection refused to stdio

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Security Considerations

  • Process isolation: External MCP server runs as separate process
  • No credential storage: Connection URLs configured via environment variables
  • Audit logging: All tool calls can be logged with --trace flag
  • Graceful degradation: Agent doesn’t crash when server unavailable

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Relationship to MCP Client Mixin

This agent is a specific implementation of the MCP Client Mixin pattern:
ComponentMCP Client MixinCUA Agent
ScopeGeneral-purpose mixinDesktop automation agent
UsageInherit in custom agentsReady-to-use CLI
ConfigurationProgrammaticEnvironment variables
TargetSDK developersEnd users
The CUA agent validates the MCP Client Mixin architecture and provides a reference implementation.

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