75 lines
5.6 KiB
Markdown
75 lines
5.6 KiB
Markdown
## Advanced
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If you already lean on Codex every day and just need a little more control, this page collects the knobs you are most likely to reach for: tweak defaults in [Config](./config.md), add extra tools through [Model Context Protocol support](#model-context-protocol), and script full runs with [`codex exec`](./exec.md). Jump to the section you need and keep building.
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## Config quickstart {#config-quickstart}
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Most day-to-day tuning lives in `config.toml`: set approval + sandbox presets, pin model defaults, and add MCP server launchers. The [Config guide](./config.md) walks through every option and provides copy-paste examples for common setups.
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## Tracing / verbose logging {#tracing-verbose-logging}
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Because Codex is written in Rust, it honors the `RUST_LOG` environment variable to configure its logging behavior.
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The TUI defaults to `RUST_LOG=codex_core=info,codex_tui=info,codex_rmcp_client=info` and log messages are written to `~/.codex/log/codex-tui.log`, so you can leave the following running in a separate terminal to monitor log messages as they are written:
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```bash
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tail -F ~/.codex/log/codex-tui.log
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```
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By comparison, the non-interactive mode (`codex exec`) defaults to `RUST_LOG=error`, but messages are printed inline, so there is no need to monitor a separate file.
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See the Rust documentation on [`RUST_LOG`](https://docs.rs/env_logger/latest/env_logger/#enabling-logging) for more information on the configuration options.
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## Model Context Protocol (MCP) {#model-context-protocol}
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The Codex CLI and IDE extension is a MCP client which means that it can be configured to connect to MCP servers. For more information, refer to the [`config docs`](./config.md#mcp-integration).
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## Using Codex as an MCP Server {#mcp-server}
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The Codex CLI can also be run as an MCP _server_ via `codex mcp-server`. For example, you can use `codex mcp-server` to make Codex available as a tool inside of a multi-agent framework like the OpenAI [Agents SDK](https://platform.openai.com/docs/guides/agents). Use `codex mcp` separately to add/list/get/remove MCP server launchers in your configuration.
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### Codex MCP Server Quickstart {#mcp-server-quickstart}
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You can launch a Codex MCP server with the [Model Context Protocol Inspector](https://modelcontextprotocol.io/legacy/tools/inspector):
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```bash
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npx @modelcontextprotocol/inspector codex mcp-server
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```
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Send a `tools/list` request and you will see that there are two tools available:
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**`codex`** - Run a Codex session. Accepts configuration parameters matching the Codex Config struct. The `codex` tool takes the following properties:
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| Property | Type | Description |
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| ----------------------- | ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------ |
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| **`prompt`** (required) | string | The initial user prompt to start the Codex conversation. |
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| `approval-policy` | string | Approval policy for shell commands generated by the model: `untrusted`, `on-failure`, `on-request`, `never`. |
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| `base-instructions` | string | The set of instructions to use instead of the default ones. |
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| `config` | object | Individual [config settings](https://github.com/openai/codex/blob/main/docs/config.md#config) that will override what is in `$CODEX_HOME/config.toml`. |
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| `cwd` | string | Working directory for the session. If relative, resolved against the server process's current directory. |
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| `model` | string | Optional override for the model name (e.g. `o3`, `o4-mini`). |
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| `profile` | string | Configuration profile from `config.toml` to specify default options. |
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| `sandbox` | string | Sandbox mode: `read-only`, `workspace-write`, or `danger-full-access`. |
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**`codex-reply`** - Continue a Codex session by providing the conversation id and prompt. The `codex-reply` tool takes the following properties:
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| Property | Type | Description |
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| ------------------------------- | ------ | -------------------------------------------------------- |
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| **`prompt`** (required) | string | The next user prompt to continue the Codex conversation. |
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| **`conversationId`** (required) | string | The id of the conversation to continue. |
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### Trying it Out {#mcp-server-trying-it-out}
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> [!TIP]
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> Codex often takes a few minutes to run. To accommodate this, adjust the MCP inspector's Request and Total timeouts to 600000ms (10 minutes) under ⛭ Configuration.
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Use the MCP inspector and `codex mcp-server` to build a simple tic-tac-toe game with the following settings:
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**approval-policy:** never
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**prompt:** Implement a simple tic-tac-toe game with HTML, JavaScript, and CSS. Write the game in a single file called index.html.
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**sandbox:** workspace-write
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Click "Run Tool" and you should see a list of events emitted from the Codex MCP server as it builds the game.
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