This analysis organizes the evidence behind Claude Code Runs an Agent Loop, Not Better Autocomplete, then explains the practical implications, trade-offs and current limits.
Read the evidence below as a decision trail: what changed, why it matters, which trade-offs shaped the result, and where the conclusion still depends on context.
Claude Code looks like the same type of tool as Cursor and Copilot, but after using it, you will find that it is completely different. The difference is not in how strong the completion is, but in that it runs an "Agentic Loop" - reception, planning, execution, verification, and if it fails to meet the standards, it will go around again. The point of learning it is not the more powerful commands, but how to cooperate with an Agent that can run in a circle by itself.
The first time I used Claude Code, I installed it with the expectation of "stronger Copilot". It was really smooth in the first few minutes - I asked it to write a utility function and drop a bug log, and everything happened quickly. But by the second week of using it, something started to feel wrong: it wasn’t doing the same kind of interactions I had with Copilot. Copilot is to fill in the next line for you; Claude Code is to read the file, run grep, modify three files, run tests to confirm after receiving a sentence, and come back to tell you that it is done.
This isn't an evolution of the completion tool, it's something else entirely. The difference lies in the "Agentic Loop". Once you see clearly that it is running this loop, you will understand why memorizing more prompt templates is useless - what you need to learn is how to cooperate with an Agent that can run loops by itself.
What is Agentic Loop: A 5-Step Breakdown
The Anthropic course splits the Agentic Loop into 5 steps: you issue a prompt, Claude collects the context (read files, run tools), perform actions (change files, run commands), verify the results, stop and wait for the next prompt if achieved, and return to the second step if not achieved. The entire process continues to loop within the session until the result is "complete and verifiable".
5 steps sounds neat, but what really separates Claude Code from the completion tool is step 4 — verify。
The completion tool does not have verify. It helps you fill in a line, generates a function, and gives you a suggestion; whether it is correct or not is up to you. Agent is different. After running an action, it will look back and ask, "Is this done?" If it doesn't finish, it will do another circle on its own - read the file again, change it again, and run the test again. What you want is no longer "the right answer the first time" but "the last correct answer". It's normal to look back several times in the middle.
The reason why most people use Claude Code is because they use it as a one-turn tool—after placing the prompt, receiving the result, and then complaining if they are not satisfied. But the design premise of this tool is that it can "run back into a circle by itself." You can only give instructions outside the loop; to enter the loop and cooperate with it, you have to know what it is doing at each step, when to interrupt, and when to fill in the context.
Verify This step is also why Plan Mode (will be discussed in the next paragraph) is so useful - it essentially changes the timing of verify from "after the action" to "before the action". Aligning the plan once in advance can save several rounds of repeated verification, debugging, and revision afterwards.
So what you want to change is not the prompt, but the collaboration mode.
After seeing clearly that it is an Agentic Loop, the next question is naturally "How do I cooperate with this loop?" The “take one thing away” level suggestion in the Anthropic course is the Explore → Plan → Code → Commit workflow – four stages, but what really changes the way it is used is one of them Plan Mode。
Plan Mode is a special execution state of Claude Code: it only uses read-only tools to read the codebase, perform necessary network queries, ask clarification questions back and forth with you, and finally produce a complete implementation plan. However,No files have been touched yet. After you read the plan and feel it is OK, click approve and then the actual writing begins. Shift+Tab will go over it.
The difference between not using Plan Mode and after using it
I didn't use Plan Mode when I wrote the first three early small projects (gwarket-site, blog-writer, publish-tools). The habit at that time was to "throw a requirement to it, check whether it is correct, and then throw a correction if it is not" - this was a reflex action of using Agent as a single-turn tool. Each feature requires two or three rounds of debugging: it writes the main logic correctly but uses a library I don't want, the file structure is inconsistent with other parts of the project, and I reinvent something but I actually already have a utility. Every time you repair one, run another round of Agentic Loop. The token will be burned quickly and the context will be accumulated quickly.
Later, I switched to Plan Mode: first lay out the plan, go through it with it "which files should be changed, what dependencies should be used, and how to verify the expected results", and then execute it after alignment. The difference is not slower or faster;Correction cost has been moved from post-debugging to pre-discussion. Debug afterwards and burn one round of Agentic Loop at a time; discuss in advance and burn only a few read-only actions.
But Plan Mode is not all of Agent collaboration. No matter how good a plan is, it will be inaccurate in the middle and later stages of the session because the context is used up - this is another bottleneck of Agentic Loop, and it is also a topic to be dealt with in the second part of this series.
Why the Permission pattern is more important than you think
Plan Mode is one of the three modes of Claude Code, the other two are approval and auto-accept. All three are switched by Shift+Tab:
- Approval: Every time I change a file or run a command, I will ask you first.
- Auto-accept: The file change will be automatically accepted, but you will still be asked when running the command.
- Plan: Use the read-only tool to give you a plan first, and then execute it after approval
These three modes are not the difference between "advanced" vs "backward";How much autonomy do you want to give the Agent?design problem. I almost always used auto-accept - it's fast, doesn't interrupt my thoughts, and seems to be the most efficient. But after watching the course, I re-examined this habit: auto-accept is suitable for tasks such as "small modifications in a single file, and I can see the corrections immediately."Cross-file reconstruction, dependency will be affected, and git history will be encountered It is reasonable to go back to approval - not because the Agent cannot be trusted, but because once such modifications go wrong, the cost of rolling back is higher than pressing approve every time.
Plan Mode is one step further on this spectrum: it lays out the plan before the Agent takes action, and puts alignment before execution. The use of the three modes in the right situation is a real design issue for Agent collaboration, not a technical issue.
My point of view: What you need to learn to learn it is not instructions, but collaboration.
After seeing Agentic Loop clearly, the biggest change was not the speed of using Claude Code, but how I thought about it.
It is not an evolution of Copilot. Copilot deals with "what should be written in the next line"; Claude Code deals with "how to achieve PR from scratch for this feature". The gap in the middle is not model strength, but tool paradigm. One is completion and the other is collaboration. What you need to learn to learn it is not the command skills, but the collaboration model.
If this article wants to leave a real takeaway for readers to take away — Plan Mode is the feature that I originally underestimated the most.. When I was watching the course, I thought, "Isn't this just asking the AI to think first? What's so great about it?" But after actually using it, I discovered that it is the core interface for agent collaboration: moving the cost of "correcting the course" from post-debugging to pre-discussion is the most important trade-off in the design of this tool.
The real learning curve of Claude Code is not in the instructions, but in the collaboration mode. Agent collaboration has a bottleneck that no one talks about but is actually the core bottleneck - context management. This is the topic dealt with in Part 2 of the series.
Practical questions and boundaries
What is the difference between Claude Code and Cursor / Copilot?
The most immediate difference is the Agentic Loop. Cursor / Copilot is an enhanced version of the completion tool - you type and it suggests the next paragraph; whether it is correct or not is your business. Claude Code is different. When it receives a sentence, it will split tasks, read files, change files, run commands, and verify results. If it fails to meet the standards, it will do another round. It is not on the same spectrum as Cursor / Copilot - the former is completion and the latter is Agent. What you need to learn to learn it is also different: what the completion tool learns is "how to make its suggestions more accurate", and what the agent learns is "how to collaborate with it."
Do I need to use Plan Mode every time?
No. The guideline is to look at "correction costs."Should use Plan Mode: Modifications across multiple files, changing dependencies or schemas, unfamiliar codebases, features that require multiple steps to run through - the cost of debugging after the fact is much greater than discussing in advance.No need for Plan Mode: Single-file small changes, clearly known utility functions, small tasks that can be explained clearly in one sentence - at this time, Plan Mode is over-engineering, and the burned read-only action is not cost-effective.
This is Part 1 of Claude’s Code 101 series:
- Article 1: Claude Code is not a stronger completion - it is essentially Agentic Loop (this article)
- Article 2: Context is the scarce resource of Claude Code (published,https://gwarket.com/claude-code-context-management/）
- Article 3: Why I wrote these 7 things as Skills - a PM’s customized judgment (to be released)
Some of the concepts in this article are based on the Anthropic open course Claude Code 101 (https://anthropic.skilljar.com/claude-code-101). The content of the article is the author's own study notes and observations, not a translation or paraphrase of the course.
What to take away
The article's value is in the evidence and trade-offs behind Claude Code Runs an Agent Loop, Not Better Autocomplete, not in treating the conclusion as universal.