Permissions

Control how your agent uses tools with permission modes, hooks, and declarative allow/deny rules.

Official Documentation: This guide is based on the official Claude Agent SDK documentation. Examples are adapted for Elixir.

The Elixir SDK provides permission controls to manage how Claude uses tools. Use permission modes and tool rules to define what is allowed automatically, and the permission_prompt_tool option to delegate decisions at runtime.

This page covers permission modes and rules. To build interactive approval flows where users approve or deny tool requests at runtime, see Handle approvals and user input.

How permissions are evaluated

When Claude requests a tool, the SDK checks permissions in this order:

1. Hooks -- Run hooks first, which can allow, deny, or continue to the next step.
2. Permission rules -- Check rules defined in settings (via the :settings option or settings files loaded by :setting_sources) in this order: deny rules first (block regardless of other rules), then allow rules (permit if matched), then ask rules (prompt for approval). These declarative rules let you pre-approve, block, or require approval for specific tools without writing code.
3. Permission mode -- Apply the active permission mode (:default, :accept_edits, :bypass_permissions, :plan, :delegate, :dont_ask).
4. Permission prompt tool -- If not resolved by rules or modes, call your permission_prompt_tool MCP tool for a decision.

This page focuses on permission modes (step 3), the static configuration that controls default behavior. For the other steps:

• Hooks: run custom code to allow, deny, or modify tool requests. See Control execution with hooks.
• Permission rules: configure declarative allow/deny rules in settings. See Secure Deployment and Permission settings.
• Permission prompt tool: delegate permission decisions to an MCP tool at runtime. See Handle approvals and user input.

Permission modes

Permission modes provide global control over how Claude uses tools. You can set the permission mode when calling ClaudeCode.query/2, when starting a session, or change it dynamically during streaming sessions.

Available modes

The SDK supports these permission modes:

Warning: When using :bypass_permissions, all subagents inherit this mode and it cannot be overridden. Subagents may have different system prompts and less constrained behavior than your main agent. Enabling :bypass_permissions grants them full, autonomous system access without any approval prompts.

Set permission mode

You can set the permission mode once when starting a query or session, or change it dynamically while the session is active.

At session start:

{:ok, session} = ClaudeCode.start_link(
  permission_mode: :accept_edits
)

Per-query override:

# Session starts in default mode
{:ok, session} = ClaudeCode.start_link(permission_mode: :default)

# Override to accept_edits for this specific query
session
|> ClaudeCode.stream("Refactor this module", permission_mode: :accept_edits)
|> ClaudeCode.Stream.text_content()
|> Enum.each(&IO.write/1)

During streaming (dynamic change):

Call ClaudeCode.set_permission_mode/2 to change the mode mid-session. The new mode takes effect immediately for all subsequent tool requests. This lets you start restrictive and loosen permissions as trust builds -- for example, switching to :accept_edits after reviewing Claude's initial approach.

{:ok, session} = ClaudeCode.start_link(permission_mode: :default)

# Change mode dynamically mid-session
{:ok, _} = ClaudeCode.set_permission_mode(session, :accept_edits)

# Subsequent queries use the new permission mode
session
|> ClaudeCode.stream("Now refactor the module")
|> ClaudeCode.Stream.text_content()
|> Enum.each(&IO.write/1)

Mode details

Accept edits mode (:accept_edits)

Auto-approves file operations so Claude can edit code without prompting. Other tools (like Bash commands that aren't filesystem operations) still require normal permissions.

Auto-approved operations:

• File edits (Edit, Write tools)
• Filesystem commands: mkdir, touch, rm, mv, cp

Use when: you trust Claude's edits and want faster iteration, such as during prototyping or when working in an isolated directory.

Bypass permissions mode (:bypass_permissions)

Auto-approves all tool uses without prompts. Hooks still execute and can block operations if needed.

Warning: Use with extreme caution. Claude has full system access in this mode. Only use in controlled environments where you trust all possible operations.

The Elixir SDK requires allow_dangerously_skip_permissions: true to enable this mode:

{:ok, session} = ClaudeCode.start_link(
  permission_mode: :bypass_permissions,
  allow_dangerously_skip_permissions: true
)

For additional isolation, combine with the :sandbox option to restrict bash command execution:

{:ok, session} = ClaudeCode.start_link(
  permission_mode: :bypass_permissions,
  allow_dangerously_skip_permissions: true,
  sandbox: %{
    "environment" => "docker",
    "container" => "my-sandbox"
  }
)

Plan mode (:plan)

Prevents tool execution entirely. Claude can analyze code and create plans but cannot make changes. Claude may use AskUserQuestion to clarify requirements before finalizing the plan. See Handle approvals and user input for handling these prompts.

Use when: you want Claude to propose changes without executing them, such as during code review or when you need to approve changes before they're made.

{:ok, result} = ClaudeCode.query(
  "How should we restructure the authentication module?",
  permission_mode: :plan,
  system_prompt: "Analyze the codebase and propose a refactoring plan."
)

Related resources

For the other steps in the permission evaluation flow:

• Handle approvals and user input -- Interactive approval prompts and clarifying questions
• Hooks -- Run custom code at key points in the agent lifecycle
• Permission rules -- Declarative allow/deny rules in settings
• Secure Deployment -- Permission rules, sandboxing, and production security
• MCP -- Connect external tools via MCP servers