Guide · Agent skill
How to use the Migration Instructions Generator agent skill
Updated · written with AI from the project's own documentation and checked against our catalogue data
This guide explains how to install and use the Migration Instructions Generator, an agent skill from github/awesome-copilot (MIT licence) named generate-custom-instructions-from-codebase. An agent skill is a folder containing a SKILL.md file that gives an AI agent a set of instructions for a specific task. After reading, you will know what the skill produces, how to add it to Claude, and how to ask for a migration guide in plain language.
Migration Instructions Generatorgithub/awesome-copilot · MIT Download the skill Quick start
- 1Download the ZIP. Download the skill's ZIP file from this page.
- 2Unzip the skill. Unzip the file and place the folder in ~/.claude/skills/ for personal use, or in a project's .claude/skills/ folder for one project.
- 3Confirm git references. Make sure the project's git history contains the two branches, commits or tags you want to compare.
- 4Ask in plain language. Request migration instructions and name the source and target references and the scope to analyse.
- 5Review the output. Open .github/copilot-migration-instructions.md and check each rule against real code and tests.
What the skill makes the agent do
The skill asks the agent to compare two states of a codebase, such as before and after a framework upgrade. The two states are referred to as the source and target references, and each can be a branch, commit or tag. The agent looks at folder structure, configuration files, and code changes between the two states.
From that comparison, the agent writes a file called .github/copilot-migration-instructions.md. The file lists old-to-new code patterns, API replacements, and obsolete patterns, so GitHub Copilot can apply the same changes consistently in later edits.
The skill is written mainly for GitHub Copilot. It is a prompt and configuration template rather than a tool with its own code.
Install the skill in Claude
Download the ZIP file for this skill from this page and unzip it. To make it available across all your projects, place the unzipped folder in ~/.claude/skills/. To make it available only inside one project, place it in that project's .claude/skills/ folder.
You can also upload the skill in the Claude apps. Open Settings, go to Capabilities, then choose Skills and upload the skill.
- Personal install: ~/.claude/skills/
- Project install: .claude/skills/ inside your project
Check the requirements before you start
The agent must be able to read both versions of the code. In practice that means your project's git history must contain the two references you want to compare, such as branches, commits or tags. The analysis depends on the actual diff, so without access to both states the output will not be reliable.
The skill does not run any scripts and does not use the network.
- Git history with both references (branches, commits or tags) available
- No scripts are run by this skill
- No network use by this skill
Trigger the skill with a natural request
You do not need a special command. Describe the migration in plain language and name the two references to compare. The agent should pick up the skill from its description and produce the migration instructions file.
Name the migration type if you can, for example a framework version upgrade, a technology migration, or an architecture refactoring. Say which scope to analyse, such as the entire project, one folder, or only modified files.
- Compare the branch v1-legacy with main and write Copilot migration instructions for the framework upgrade.
- Analyse only the src/api folder between commit abc123 and the tag v2.0, and create the migration instructions file.
- Generate Copilot migration instructions for moving from jQuery to React, comparing the main branch with the react-migration branch.
Review the generated instructions
Read the generated .github/copilot-migration-instructions.md before relying on it. The skill's own text says human validation matters for complex cases, so check the old-to-new rules against your code and tests.
The file includes sections for mandatory transformations, transformations that need validation, API correspondences, new patterns to adopt, and obsolete patterns to avoid. It also lists situations that need manual escalation.
- Check each old-to-new rule against a real example from your code.
- Run your tests after applying a transformation.
- Remove or adjust rules that produce false positives.
When this skill is not the right choice
The output is a long instruction document, so it adds overhead for a simple one-off edit. It is also a poor fit for unattended automated rewrites of production code, because the generated rules may be wrong.
- Simple one-off code edits
- Projects where the agent cannot read both versions
- Unattended automated rewrites of production code
What people use it for
- Documenting a framework version upgrade so Copilot follows the same transformation rules afterwards.
- Recording a technology swap, such as jQuery to React, as a written reference for the team.
- Capturing the changes from a large architecture refactoring for future similar work.
- Enforcing consistent conventions across a codebase during a migration.
Frequently asked questions
How do I install the generate-custom-instructions-from-codebase skill?
Download the skill's ZIP file from this page and unzip it. Place the folder in ~/.claude/skills/ for personal use, or in a project's .claude/skills/ folder for one project. You can also upload it in the Claude apps under Settings, then Capabilities, then Skills.
What does the migration instructions generator produce?
It produces a file called .github/copilot-migration-instructions.md. The file lists old-to-new code patterns, API replacements, and obsolete patterns so GitHub Copilot can apply the same changes consistently in future edits.
What do I need to use this skill?
You need access to the project's git history with the two references to compare, such as branches, commits or tags. The skill runs no scripts and uses no network.
Is this skill free?
The skill is published under the MIT licence in the github/awesome-copilot repository. This page does not state pricing beyond that licence.
Does the skill run code or access the internet?
No. According to the skill's description, it runs no scripts and uses no network. It is a prompt and configuration template rather than a tool with its own code.
Can I use this instead of a manual migration guide?
It can help draft one, but the source says the generated rules may be wrong and human validation matters for complex cases. Review the output before relying on it.
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Our verdict
Use this skill if you are doing a framework upgrade, technology swap or large refactor and want a written, reviewable record that Copilot can follow afterwards. Skip it for simple one-off edits or for unattended rewrites of production code, where its generated rules need careful human checking.
Download the skill