Claude Code Mods are a new way to customize how Claude Code behaves. Instead of only changing settings, permissions or commands, developers can write small TypeScript functions that change prompts, intercept tool calls, modify permissions and even add custom terminal interfaces.
Anthropic introduced Mods on October 1, 2026. They are designed for developers who want Claude Code to fit a specific workflow instead of waiting for a built-in feature.
What are Claude Code Mods?
A Claude Code Mod is a small TypeScript function that hooks into events inside Claude Code. A mod can run before an event, after it, instead of it, or around it.
That gives developers more control than traditional configuration files or simple hooks.
For example, a Mod can:
- rewrite a prompt before it reaches the model
- block or change a tool call
- retry a tool call
- approve or deny a permission request
- remove sensitive information from tool output
- add a custom terminal interface
- replace part of Claude Code's normal behavior
Mods are distributed through Claude Code plugins, so developers can build them locally and share them in the same general way as other plugins.
How Claude Code Mods work
Claude Code produces events while a session is running. These events can represent actions such as tool calls, permission requests or changes to the terminal interface.
A Mod attaches code to one or more of those events.
The important difference is that a Mod can do more than simply observe an event. Depending on the hook, it can change what happens next.
That makes Mods useful for workflows where a developer wants an extra control layer around Claude Code.
What can you build with Mods?
Anthropic's examples show several practical directions.
A developer could create a context-window display that shows how full the current session is. Another Mod could show the expected impact of a shell command before allowing it to run. A third could record changes made during a session and provide a way to review those changes.
For a development team, Mods could also be used for internal policies. A team could create checks around sensitive commands, add warnings before destructive operations, or redact certain information from tool results.
Claude Code Mods vs hooks
Hooks already gave Claude Code a way to react to certain events. Mods extend that idea.
Hooks are useful when you need a predefined action around an event. Mods are more suitable when you want to change the behavior itself or build a custom interface.
For example, a hook might run a validation command after a change. A Mod could intercept the underlying tool call, inspect it, display additional information and decide whether the action should continue.
The choice depends on how much control your workflow needs.
The biggest security issue with Claude Code Mods
Mods should be treated like code that you install on your computer.
Anthropic explicitly says Mods have the same access to your machine as Claude Code itself. They are not sandboxed.
That means a malicious Mod could be dangerous. A developer should not install a Mod simply because it looks useful or has a good README.
Before installing a third-party Mod:
- check who created it
- read the source code when possible
- check the plugin contents
- look for shell commands and filesystem access
- check whether it sends information to external services
- avoid installing code from an unknown source into a sensitive development environment
Which Claude Code version supports Mods?
Anthropic's developer guide says Mods require Claude Code 2.1.287 or later. Mods are enabled by default in supported versions.
The API can change between Claude Code releases, so developers should use the type declarations generated for their installed version as the authority when building a Mod.
How Mods can help development teams
Mods are most useful when they solve a repeated workflow problem.
A team could use them to add project-specific checks, show useful development information in the terminal, enforce safer tool usage, or improve the way code changes are reviewed.
They can also reduce the need to maintain complicated instructions in every project because some behavior can be implemented directly in the development environment.
What developers should not do
Do not treat Mods as harmless configuration files.
A Mod can influence how Claude Code interacts with your system. That makes source review, permissions and trusted distribution important parts of using the feature.
For production development environments, teams should consider maintaining an approved list of Mods and reviewing changes before they are distributed internally.
Claude Code Mods are useful, but trust matters
Mods make Claude Code much more flexible. Developers can change behavior, add controls and create interfaces that match the way their teams work.
The trade-off is access. Because Mods run with the same machine access as Claude Code, customization also becomes a software-supply-chain concern.
The safest approach is simple: use Mods for clear workflow problems, inspect the code you install, and treat third-party Mods with the same caution you would give any other executable developer tool.