The difference between AI agents and AI assistants

Greg Foster
Greg Foster
Graphite software engineer
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Table of contents

AI assistants are reactive tools that respond to explicit user commands and perform tasks accordingly — examples include Siri, Alexa, or ChatGPT that await each prompt to act

AI agents, on the other hand, are proactive, goal-driven systems. Once given an objective, they autonomously plan and execute workflows, sometimes using external tools or memory, with minimal ongoing prompting

CharacteristicAI assistant (reactive)AI agent (proactive)
AutonomyRequires frequent user inputOperates independently once given a goal
Control flowPrompt → responseGoal → planning → execution
Memory & contextOften stateless or short-livedMay maintain memory, handle multi-step workflows
ComplexitySuited for simple, defined tasksBuilt for complex, autonomous, long-running tasks
Computational loadLowerHigher, due to reasoning, monitoring, and planning requirements

Graphite is a unified developer platform designed to help engineering teams ship higher-quality software, faster—with deep integration into GitHub, VS Code, and CI/CD workflows. Graphite embodies both AI paradigms in a single workflow:

  • Diamond acts as the autonomous agentic layer, proactively reviewing every PR, surfacing critical issues, and offering instant suggestions without any user input.
  • Graphite Chat serves as the reactive assistant, giving developers a conversational interface for deep dives, clarifications, targeted fixes, and quick action within the pull request.

Graphite demonstrates both models: Diamond acts autonomously with agentic behavior; Graphite Chat remains a reactive, prompt-driven assistant within developer workflows.

AI assistants are reactive—they await and respond to user prompts. AI agents are proactive—once provided with a goal, they can independently plan and execute a series of actions to meet that objective

Both rely on large language models for natural language understanding. Assistants use LLMs to interpret prompts and return responses. Agents leverage LLMs for reasoning, planning, tool use, and autonomous action over extended tasks

Assistants: Siri, Alexa, ChatGPT help with routine tasks on demand. Agents: Autonomous systems like code review tools, content moderation systems, or Graphite's Diamond—once initiated, they act independently toward their goals

Agents are more complex to build, can be costly, prone to errors in unsupervised operation, and require monitoring to avoid going off-track

Graphite integrates both approaches: Diamond automates high-signal, context-aware code reviews (agent), while Graphite Chat offers an interactive assistant for on-demand feedback. Together, they streamline review workflows, enforce standards, and assist in PR management with less friction

If you need simple, prompt-driven help (like drafting, summarizing, searching), an assistant fits best. If you're aiming to automate complex workflows or repeatable multi-step tasks with minimal fuss later, agentic solutions offer more autonomy and efficiency—though at higher complexity.

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