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How to use Cursor Agent for beginners

David Ondrej·
5 min read

Based on David Ondrej's video on YouTube. If you like this content, support the original creators by watching, liking and subscribing to their content.

TL;DR

Cursor’s agent can autonomously edit multiple files and issue terminal commands, accelerating prototype creation beyond simple code suggestions.

Briefing

Cursor’s newly released AI agent can do more than generate code snippets: it can autonomously make multi-file changes across a codebase and even run terminal commands, turning a coding assistant into a hands-on “side-by-side” developer. That shift matters because it compresses the time from idea to working prototype—especially for people who don’t want to manually wire up every file, dependency, and UI component line by line.

The walkthrough starts with setup: download Cursor for Mac or Windows, create an account, and choose a model that supports the agent. The agent feature only works with “clo” models, so the recommended selection is Sonnet 3.5; if it’s not visible, the user enables models in Cursor settings. With the agent enabled, the plan is to build a full-stack web app modeled after Voiceflow’s block-based canvas, using Next.js plus Twilio capabilities (SMS, voice, email, and authentication).

From there, the agent takes over the scaffolding. It creates the Next.js project, installs required packages, and generates the initial file structure—then continues by editing multiple files to assemble the UI. Cursor’s “rules” system is highlighted as a key productivity lever: a project-specific cursor rules file can be copied from a template and applied to future agent instructions, helping keep behavior consistent across the build. The agent also supports iterative collaboration: while it’s running, the user can ask follow-up questions in chat and request a roadmap or targeted fixes across the indexed codebase.

A major theme is context and review. The agent indexes the codebase rather than pulling random fragments, which improves suggestion accuracy. Still, changes must be reviewed before acceptance—blindly applying edits can break the system, especially when environment variables or front-end behavior are involved. The presenter demonstrates this by accepting the agent’s initial front-end, then repeatedly prompting for UI adjustments (icon colors, component creation, block behavior) and Twilio-specific features.

The build becomes a live debugging exercise. The canvas interaction—connecting blocks by dragging from “dots”—fails in early attempts, producing errors and rendering glitches (including duplicated elements). The workflow emphasizes giving the agent precise, relevant context (including screenshots) and using concise repair prompts like “implement the fix in the simplest way possible.” When the line-connection approach proves buggy, the strategy shifts: instead of drawing lines, the app is simplified so blocks snap to each other on the canvas edges, and new blocks are created only via the sidebar icons. That change reduces complexity and stabilizes the prototype.

By the end, the app achieves a working block-snapping interaction for the Voiceflow-like experience, with Twilio blocks integrated at a basic level. The broader takeaway is practical: AI agents can accelerate development dramatically, but success still depends on active learning—reading diffs, iterating prompts, and treating errors as part of the compounding skill-building process. The presenter contrasts this with faster no-code tools like Bolt for quick demos, arguing Cursor is better for deeper customization and real functionality needed for startups or production-adjacent projects.

Cornell Notes

Cursor’s agent upgrades coding from “generate a few lines” to “perform multi-file edits and run terminal commands,” enabling faster prototype building. The tutorial walks through setting up Cursor, selecting the right agent-capable model (Sonnet 3.5), and using the agent to scaffold a Next.js app that mimics Voiceflow’s block canvas while integrating Twilio features (SMS, voice, email, authentication). A key learning tool is Cursor rules, which apply project-specific instructions across the build. The process repeatedly alternates between accepting agent changes, reviewing diffs, prompting for targeted UI behavior, and debugging canvas interactions using screenshots and concise fix requests. When line-drawing connections become too glitchy, simplifying to edge snapping stabilizes the prototype quickly.

What makes Cursor’s agent different from earlier code assistants in this workflow?

It can autonomously perform multi-file edits across a codebase and can write terminal commands, not just suggest code fragments. It also indexes the project for full contextual understanding, which improves the accuracy of edits and suggestions compared with approaches that only pull small code snippets into the model’s context.

Why does model selection matter for using the agent feature?

The agent feature only works with “clo” models. The tutorial recommends Sonnet 3.5 as the default. If Sonnet 3.5 isn’t visible, the user must enable models in Cursor settings under the models section.

How does Cursor rules help during a multi-step build?

A project-specific cursor rules file (named exactly “cursor rules”) can store a system prompt/instructions optimized for the user’s style. Once saved, it applies to future agent messages within that project, reducing the need to restate preferences and improving consistency across iterations.

What’s the recommended approach when the agent makes changes that affect UI behavior?

Review the diff and accept changes intentionally rather than blindly. The tutorial shows accepting initial front-end edits, then iterating: adjusting icon colors for contrast, creating components for draggable blocks, and prompting for specific canvas interactions. When behavior breaks (errors or glitches), the workflow shifts to targeted prompts and screenshot-based context.

How does the tutorial handle a persistent bug in the block-connection feature?

It tries line-drawing first (dragging from dots to create a line that follows the cursor), but glitches and duplication appear. The fix strategy evolves: provide more precise context (including screenshots), tag the relevant file (e.g., block-related TSX), and request the simplest fix. When that still doesn’t stabilize, it changes the design constraint—switching from line connections to edge snapping and restricting new block creation to the sidebar icons.

What’s the practical lesson about using AI tools during debugging?

Errors shouldn’t be treated as personal failure. The workflow encourages learning from failures by understanding what caused the issue, trying targeted fixes, and iterating prompts. Over time, this builds competence and reduces future friction—similar to compounding returns, where earlier effort makes later work faster.

Review Questions

  1. What specific capabilities (multi-file edits, terminal commands, codebase indexing) enable the Cursor agent to act more like a developer than a snippet generator?
  2. How do Cursor rules and model selection work together to make agent-driven builds more reliable?
  3. When the canvas line-connection feature became unstable, what design simplification was used to restore functionality?

Key Points

  1. 1

    Cursor’s agent can autonomously edit multiple files and issue terminal commands, accelerating prototype creation beyond simple code suggestions.

  2. 2

    Agent mode requires selecting an agent-capable model (Sonnet 3.5 is recommended); if it’s missing, enable models in Cursor settings.

  3. 3

    Use a project-specific “cursor rules” file to lock in instructions and reduce repeated prompt overhead during long builds.

  4. 4

    Accept agent changes only after reviewing diffs, especially when environment variables, UI behavior, or canvas interactions are involved.

  5. 5

    Debugging works best with precise prompts plus relevant screenshots, and with concise repair requests like “implement the fix in the simplest way possible.”

  6. 6

    When a complex interaction (like line-drawing between blocks) keeps glitching, simplifying the interaction model (edge snapping and sidebar-only block creation) can stabilize the prototype quickly.

  7. 7

    No-code tools may be faster for demos, but Cursor’s IDE-level control is positioned as better for deeper customization and startup-grade functionality.

Highlights

Cursor’s agent can make multi-file changes and run terminal commands, effectively acting like an active coding partner rather than a passive autocomplete.
Cursor rules (in a file named exactly “cursor rules”) provides project-wide instruction consistency, making multi-step agent workflows more dependable.
The tutorial demonstrates a realistic debugging loop: prompt → accept diffs → test UI → screenshot errors → targeted fixes → redesign constraints when necessary.
A persistent canvas connection bug was resolved by switching from line rendering to edge snapping and restricting block creation to the sidebar.

Topics

  • Cursor Agent Setup
  • Sonnet 3.5 Models
  • Cursor Rules
  • Next.js Canvas UI
  • Twilio Blocks

Mentioned