Configuring Codex

Codex should work out of the box for most users. But sometimes you want to configure Codex to your own liking to better suit your needs. For this there is a wide range of configuration options.

Codex configuration file

The configuration file for Codex is located at ~/.codex/config.toml.

To access the configuration file when you are using the Codex IDE extension, you can click the gear icon in the top right corner of the extension and then clicking Codex Settings > Open config.toml.

This configuration file is shared between the CLI and the IDE extension and can be used to configure things like the default model, approval policies, sandbox settings or MCP servers that Codex should have access to.

High level configuration options

Codex provides a wide range of configuration options. Some of the most commonly changed settings are:

Default model

Pick which model Codex uses by default in both the CLI and IDE.

Using config.toml:

model = "gpt-5"

Using CLI arguments:

codex --model gpt-5

Model provider

Select the backend provider referenced by the active model. Be sure to define the provider in your config first.

Using config.toml:

model_provider = "ollama"

Using CLI arguments:

codex --config model_provider="ollama"

Approval prompts

Control when Codex pauses to ask before running generated commands.

Using config.toml:

approval_policy = "on-request"

Using CLI arguments:

codex --approval-policy on-request

Sandbox level

Adjust how much filesystem and network access Codex has while executing commands.

Using config.toml:

sandbox_mode = "workspace-write"

Using CLI arguments:

codex --sandbox workspace-write

Reasoning depth

Tune how much reasoning effort the model applies when supported.

Using config.toml:

model_reasoning_effort = "high"

Using CLI arguments:

codex --config model_reasoning_effort="high"

Command environment

Restrict or expand which environment variables are forwarded to spawned commands.

Using config.toml:

[shell_environment_policy]
include_only = ["PATH", "HOME"]

Using CLI arguments:

codex --config shell_environment_policy.include_only='["PATH","HOME"]'

You can also use profiles to switch between different configurations on the fly. Profiles currently apply to the Codex CLI: you can define multiple [profiles.<name>] blocks in config.toml, then launch with codex --profile my-profile to switch between completely different model, approval, or sandbox setups.

For the complete configuration reference, see the Codex config documentation on GitHub.

Personalizing the Codex IDE extension

Additionally to configuring the underlying Codex agent through your config.toml file, you can also configure the way you use the Codex IDE extension.

To see the list of available configuration options, click the gear icon in the top right corner of the extension and then click IDE settings.

To define your own keyboard shortcuts to trigger Codex or add something to the Codex context, you can click the gear icon in the top right corner of the extension and then click Keyboard shortcuts.