Introduction

The consensus is clear: developers love Claude Code for its precision and reasoning. But what if I told you that for critical, real-world tasks, like understanding a massive legacy codebase overnight, another tool is not just better, but in a different league? Let's put both tools through their paces on the psf/requests repository and build a decision framework you can use today.

The result is a crystal-clear map of when to use which tool, and why.

Both tools are especially powerful in the context of AI hackathons, where you need to ramp up on unfamiliar codebases, ship working features, and debug under tight time pressure. Whether you're joining online AI hackathons or building in-person, learning how to combine Gemini CLI and Claude Code gives you a real edge for AI hackathon projects. If you're looking for upcoming AI hackathons where you can apply these skills, explore LabLab.ai's global AI hackathons.

What You'll Learn

In this tutorial, we'll compare Gemini CLI and Claude Code across four real-world challenges:

• Challenge 1: Mapping a large codebase (50k+ lines)
• Challenge 2: Performing project-wide audits
• Challenge 3: Handling knowledge gaps with external sources
• Challenge 4: Executing autonomous development tasks

By the end, you'll have a strategic decision framework to choose the right tool for each scenario, especially when you're building under the constraints of an artificial intelligence hackathon.

Prerequisites

• A Claude subscription (Pro, Max, Teams, or Enterprise) or Claude Console account
• Node.js and npm installed (for Gemini CLI)
• Git installed

Setup

Before we dive into the challenges, let's set up both tools and prepare the test repository.

Installing Claude Code

Install Claude Code using one of the following methods:

macOS, Linux, WSL:

curl -fsSL https://claude.ai/install.sh | bash

Windows PowerShell:

irm https://claude.ai/install.ps1 | iex

Windows CMD:

curl -fsSL https://claude.ai/install.cmd -o install.cmd && install.cmd && del install.cmd

Alternatively, you can use Homebrew (macOS):

brew install --cask claude-code

Or WinGet (Windows):

winget install Anthropic.ClaudeCode

On first use, you'll be prompted to log in with your Claude account.

Installing Gemini CLI

Install Gemini CLI globally using npm:

npm install -g @google/gemini-cli

Cloning the Test Repository

We'll be testing both tools on the psf/requests repository, a popular Python HTTP library with over 50,000 lines of code. Clone the repository:

git clone https://github.com/psf/requests.git
cd requests

Note: When cloning the Requests repository, you may need to add the -c fetch.fsck.badTimezone=ignore flag to avoid an error about a bad commit timestamp:

git clone -c fetch.fsck.badTimezone=ignore https://github.com/psf/requests.git
cd requests

You're now ready to test both tools! Navigate to the requests directory and you can start using either claude or gemini commands.

Discussion

Challenge 1: Mapping the Territory, "What the hell is this codebase?"

We tasked both tools with understanding the 50k+ line requests library. And there was a big difference in the output quality. Here's what I discovered:

The Prompts

Goal: Understand the architecture of the entire psf/requests repository.

To ensure transparency and reproducibility, here are the exact prompts we used for this challenge:

Gemini CLI:

Analyze the entire psf/requests repository cloned in my current directory. Provide a concise summary of: 1) The overall project architecture and main modules, 2) The public API entry points as seen by an end-user, 3) Key dependencies and how they are used. Base this on all .py files in src/, the README.md, and pyproject.toml.

Claude Code:

I need to understand the architecture of the requests library. Start by summarizing the README.md. Then, we'll explore the src/requests/ directory step by step.

Gemini CLI: The Aerial Survey

With its 1M+ token context, Gemini ingested the entire repository—source, config, and docs—in one go. In under 15 seconds, it returned a structured JSON report explaining the library's four-layer architecture, pinpointing the critical Session/Adapter split, and listing key dependencies.

It didn't just read the code; it executed a planned investigation using a codebase_investigator agent, tracing its own steps. For a developer facing a new codebase, this is an intelligence goldmine delivered instantly.

Claude Code: The Walking Tour

Claude's approach was methodical and collaborative. It started with the README, showed me the directory structure, and summarized the public API from __init__.py. Its output was helpful and accurate, but it was a starting point for a conversation.

To build the same comprehensive understanding, I had to act as a guide: "Now look at sessions.py," "Now explain adapters.py." This dialogue is excellent for learning, but it's a slower path to a complete map.

The Verdict

• If you need the full picture fast (due diligence, security review, pre-refactor), Gemini CLI is the tool you reach for first. Its huge context window means you can throw the whole repo at it and get a clear, high-level map back in a single pass.
• Claude Code is the better fit when you want to walk the codebase together—asking follow-ups, poking at edge cases, and refining your understanding step by step.

Challenge 2: The Project-Wide Audit

We asked both tools to perform a simple audit: "Find all user-configurable timeout settings."

The Prompts

Goal: Find all user-configurable timeout settings across the codebase.

Gemini CLI:

Search all Python files in the repository for user-configurable timeout settings. Find every constant, default variable, or configuration point related to connect_timeout, read_timeout, or a general timeout. List each file, the variable name, its default value, and a one-line description of its purpose.

Claude Code:

Help me find all user-configurable timeout settings in the requests library.

Gemini CLI: The Compliance Officer

Gemini executed a lightning-fast text search across all files, filtered the 131 matches down to the relevant user-facing parameters, and presented a clean, 7-row table in about 10 seconds. It gave me exactly what I asked for: a checklist with no extra commentary.

This is the ideal output when you're performing a security review, writing documentation, or need a scoped answer fast.

Claude Code: The Systems Architect

Claude took a different path. Instead of just finding the settings, it spent a minute exploring the code to understand the entire timeout system. Its response was a mini-tutorial: it explained the three timeout formats, traced the parameter's flow through the API, Session, and Adapter layers, warned about the dangerous default of None, and mapped out the exception hierarchy.

This is the ideal output when you're learning a new codebase or designing a feature that interacts with this system.

The Verdict

• For audits, searches, and data extraction tasks, Gemini CLI is your precision tool. Its ability to scan everything and return a scoped answer is unmatched for efficiency.
• For developing a deep, contextual understanding of a system, Claude Code is your guide. Its exploratory approach and explanatory strength turn a simple query into a learning session.

Challenge 3: The Knowledge Gap Test

We asked both tools to summarize release notes for a version (2.32.5) released after their training data.

The Prompts

Goal: Get information about a release (v2.32.5) published after the models' training data.

Gemini CLI:

Let's assume you have access to the internet via an MCP server. Search for the release notes or changelog for requests version 2.32.5 and summarize the key changes.

Claude Code:

What are the key changes in the requests library version 2.32.5 compared to the previous version? Can you summarize the release notes?

Claude Code: The Codebase Detective

Claude didn't know the answer from memory. Instead, it executed a flawless investigation within the repository: It checked the version file, searched for changelogs, found HISTORY.md, and synthesized a detailed report. It provided crucial context about the reverted SSL caching feature and the version's place in the release lineage. It found truth locally.

Gemini CLI: The Web Integrator

Gemini, using its MCP server for Google Search, fetched information from the web. Its summary was accurate but brief. Interestingly, it noted the web results matched the local HISTORY.md, revealing its dual awareness.

For questions about a library's broader ecosystem, recent CVEs not documented locally, or alternative solutions from forums, this live web access is a decisive advantage.

The Verdict: A Question of Source

• For questions where the definitive answer lies within your project's own files, Claude Code's investigative approach is superior. It treats your codebase as the primary source.
• For questions about the wider world, new CVEs, latest blog posts, or APIs changed after your last commit, Gemini CLI's MCP-powered web search is your only option. It connects your development environment to the live internet.

Challenge 4: The Grunt Work ("Just get it done.")

This was the most revealing test. We gave both the same, straightforward task: "Add comprehensive type hints to src/requests/utils.py."

The Prompts

Goal: Add comprehensive type hints to a large utility file.

Gemini CLI:

Add comprehensive type hints (using Python's typing module) to all functions in the file 'src/requests/utils.py'. Preserve all existing code and logic, only add the type annotations. Output the complete, modified file.

Claude Code:

Add comprehensive type hints (using Python's typing module) to all functions in the file 'src/requests/utils.py'. Preserve all existing code and logic, only add the type annotations. Output the complete, modified file.

Note: This prompt was identical for both tools, making it a fair comparison of their execution models.

Gemini CLI: The Automated Engineer

Gemini treated this as a linear engineering task: Read → Analyze → Write → Verify. Its killer move? After writing the file, it automatically ran python -m py_compile. It found syntax errors, fixed them, re-ran the check, and iterated until it delivered a working, syntactically valid file.

The entire process required zero intervention. It's a CI/CD pipeline in a CLI.

Claude Code: The Collaborative Thinker

Claude analyzed the file and prepared a complete version with type hints. However, when it tried to write, it hit a critical error: "File has been unexpectedly modified." It detected Gemini's concurrent edits, attempted recovery, and ultimately output the proposed code as a text block in our chat. It never wrote or verified a working file. It was blocked by the very state change it couldn't control.

The Pivotal Insight: Autonomous vs. Collaborative Execution

This isn't about speed. It's about execution model.

• Gemini CLI operates like an autonomous agent. It assumes control, performs actions, verifies results, and iterates. It's built for task completion.
• Claude Code operates like a pair programmer in a shared terminal. It assumes a single-threaded, collaborative environment. When external state changed, it stopped and reported, expecting human guidance. It's built for interactive, controlled development.

The Verdict

• For autonomous, verified batch tasks (boilerplate generation, large-scale linting, adding type hints to many files), Gemini CLI is your preferred choice.
• For careful, step-by-step refactors where you maintain tight control, Claude Code is your preferred choice.

The Strategic Developer's Decision Matrix

Choosing between Gemini CLI and Claude Code isn't about picking the "best coder." It's about matching the tool to the task. Here is your cheat sheet:

| If your primary need is... | You should default to... | Because it excels at... | | ---------------------------- | ------------------------ | -----------------------------------------------------------------------------| | Comprehensive discovery | Gemini CLI | Analyzing entire codebases in one shot (1M+ token context). | | Precision & explanation | Claude Code | Deep, contextual understanding and reasoning. | | Audits & data extraction | Gemini CLI | Fast, complete scanning and returning scoped results. | | Live, external knowledge | Gemini CLI | Web search integration via MCP (CVEs, latest docs). | | Autonomous execution | Gemini CLI | Multi-step tasks (write → verify → fix) without hand-holding. | | Interactive pair programming | Claude Code | Conversational, step-by-step development with oversight. |

The Hybrid Workflow: The Pro's Setup

The most powerful approach uses both. Here's the tactical workflow:

1. Onboard with Gemini: Use gemini to get the architectural map and identify hotspots in a new repository, just like you would before an AI hackathon submission.
2. Plan with Claude: Feed Claude the complex modules: "Help me design a safe refactor for this critical session logic," and treat it like a senior teammate in a time-boxed AI hackathon project.
3. Execute & Verify with Gemini: "Now, implement this plan across the 10 affected files and run the test suite after each," so you can rapidly prototype features that are demo-ready for global AI hackathons.
4. Update with Gemini web search: "Search for any recent security discussions about the urllib3 version we're using," mirroring the kind of due diligence judges expect in serious artificial intelligence hackathon projects.

Frequently Asked Questions

How can I use Gemini CLI and Claude Code in an AI hackathon?

You can use Gemini CLI to quickly scan and understand large codebases, run automated audits, and execute multi-step refactors, while Claude Code helps you reason through tricky design decisions and edge cases in conversation. Together, they give you both speed and reliability when you're building production-like features for an AI hackathon.

Are Gemini CLI and Claude Code suitable for beginners in AI hackathons?

Yes. As long as you're comfortable with a terminal and basic Git/GitHub workflows, both tools can dramatically lower the barrier to shipping projects in AI hackathons for beginners. Claude Code is especially beginner-friendly for learning new codebases, while Gemini CLI shines once you're ready to automate repetitive tasks.

What are some AI hackathon project ideas that benefit from these tools?

Any project that touches real-world code or APIs can benefit, including observability dashboards, agentic devtools, CI assistants, and refactoring copilots. These tools are ideal when your AI hackathon ideas involve scanning large repositories, enforcing standards, or transforming code at scale.

How long does it take to learn Gemini CLI and Claude Code for an AI hackathon?

Most developers can become productive with the basics in a single weekend, especially if they already use Git and a modern IDE. You don't need to master every feature—focus on a small set of commands that help you explore code, apply changes, and validate results during a time-limited artificial intelligence hackathon.

Are there any limitations when using these tools in time-limited hackathons?

Yes. Gemini CLI is great for autonomous execution but can consume tokens quickly if you over-scope tasks, while Claude Code relies on a stable local state and can be disrupted by concurrent edits or long-running processes. In fast-paced online AI hackathons, keep your prompts focused, commit often, and test small, incremental changes to avoid debugging under deadline pressure.

Conclusion

The best developers aren't tool loyalists; they're tacticians. Claude Code is your brilliant strategist, incredible for complex reasoning and collaborative problem-solving. Gemini CLI is your relentless executor, unmatched for breadth-first analysis, live data integration, and autonomous task completion.

Your new superpower is knowing when to use each one. By understanding the strengths of both tools and applying the decision matrix we've built, you can optimize your development workflow for maximum efficiency and effectiveness in any AI hackathon environment.

Whether you're onboarding to a new codebase, performing security audits, or executing large-scale refactoring tasks, the strategic combination of both tools will give you the best of both worlds: deep understanding and autonomous execution. If you're ready to apply these skills, explore upcoming global AI hackathons on LabLab.ai and start turning this workflow into real AI hackathon projects.