How Cursor’s Coding Agent Works: Deep Dive into Its Architecture and Real‑World Experiments

Introduction

Cursor is a popular coding‑agent tool that combines a large language model with a set of backend utilities to provide context‑aware code generation, editing, compilation, and execution.

Experiment 1 – Hello World

Using the OpenAI gpt-4o model, we prompted Cursor to create a Go hello.go program, compile it with go build, and run the resulting executable hello. The tool generated the source file, built it successfully, and the program printed “Hello World!”.

Experiment 2 – Code Search

We asked Cursor to locate the CUDA flash‑attention function in the 300 k‑line llama.cpp repository. Cursor invoked the codebase_search tool with the keyword “CUDA flash attention function” and returned 17 file paths, of which only a few were relevant to the request.

ggml/src/ggml-cuda/fattn.cu
src/llama-graph.cpp
ggml/CMakeLists.txt
ggml/src/ggml-cuda/ggml-cuda.cu
ggml/src/ggml-cuda/fattn-common.cuh
ggml/src/ggml-cuda/fattn-mma-f16.cuh
ggml/src/ggml-cuda/fattn-tile-f32.cu
ggml/src/ggml-cuda/fattn-vec-f32.cuh
ggml/src/ggml-vulkan/ggml-vulkan.cpp
ggml/src/ggml.c
ggml/src/ggml-cuda/common.cuh
ggml/src/ggml-cuda/fattn-vec-f16.cuh
ggml/src/ggml-cuda/fattn-tile-f16.cu
tools/mtmd/clip.cpp
ggml/src/ggml-cpu/ggml-cpu.c
ggml/src/ggml-cann/ggml-cann.cpp
include/llama.h

Experiment 3 – Front‑end Planning

We gave Cursor a natural‑language prompt to build a single‑page “to‑do” web application using HTML5, CSS, and JavaScript. The model first created a work item, then sequentially called edit_file to generate index.html, style.css, and app.js. Finally it invoked todo_write to mark the task as completed.

Analysis

The experiments demonstrate that Cursor’s effectiveness hinges on the underlying LLM; the toolset (edit_file, run_terminal_cmd, codebase_search, etc.) is simple but powerful. When the model lacks sufficient context—such as internal build tools or ambiguous symbols—Cursor fails, underscoring the importance of rich training data, comprehensive unit tests, and clear prompts for reliable automation.