> ## Documentation Index
> Fetch the complete documentation index at: https://langchain-5e9cc07a-preview-usagev-1776718497-b6ed428.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Permissions

> Control filesystem access with declarative permission rules for Deep Agents

Control which files and directories an agent can read or write to using declarative permission rules. Pass a list of rules to `permissions=` and the agent's built-in filesystem tools respect them.

Permissions only apply to the built-in filesystem tools (`ls`, `read_file`, `glob`, `grep`, `write_file`, `edit_file`). Custom tools and MCP tools that access the filesystem are not covered. Permissions also do not apply to [sandbox backends](/oss/javascript/deepagents/sandboxes), which support arbitrary command execution via the `execute` tool.

<Tip>
  Use `permissions` when you need **path-based allow/deny rules** on the built-in filesystem tools. Use [backend policy hooks](/oss/javascript/deepagents/backends#add-policy-hooks) when you need custom validation logic (rate limiting, audit logging, content inspection) or need to control custom tools.
</Tip>

## Basic usage

## Rule structure

## Examples

## Subagent permissions

## Composite backends

***

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