README / docs refactor (#2724)
This PR cleans up the monolithic README by breaking it into a set
navigable pages under docs/ (install, getting started, configuration,
authentication, sandboxing and approvals, platform details, FAQ, ZDR,
contributing, license). The top‑level README is now more concise and
intuitive, (with corrected screenshots).
It also consolidates overlapping content from codex-rs/README.md into
the top‑level docs and updates links accordingly. The codex-rs README
remains in place for now as a pointer and for continuity.
Finally, added an extensive config reference table at the bottom of
docs/config.md.
---------
Co-authored-by: easong-openai <easong@openai.com>
2025-08-27 10:30:39 -07:00
## Advanced
## Tracing / verbose logging
Because Codex is written in Rust, it honors the `RUST_LOG` environment variable to configure its logging behavior.
The TUI defaults to `RUST_LOG=codex_core=info,codex_tui=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:
```
tail -F ~/.codex/log/codex-tui.log
```
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.
See the Rust documentation on [`RUST_LOG` ](https://docs.rs/env_logger/latest/env_logger/#enabling-logging ) for more information on the configuration options.
## Model Context Protocol (MCP)
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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#connecting-to-mcp-servers ).
README / docs refactor (#2724)
This PR cleans up the monolithic README by breaking it into a set
navigable pages under docs/ (install, getting started, configuration,
authentication, sandboxing and approvals, platform details, FAQ, ZDR,
contributing, license). The top‑level README is now more concise and
intuitive, (with corrected screenshots).
It also consolidates overlapping content from codex-rs/README.md into
the top‑level docs and updates links accordingly. The codex-rs README
remains in place for now as a pointer and for continuity.
Finally, added an extensive config reference table at the bottom of
docs/config.md.
---------
Co-authored-by: easong-openai <easong@openai.com>
2025-08-27 10:30:39 -07:00
2025-09-11 14:38:24 -07:00
## Using Codex as an MCP Server
fix: separate `codex mcp` into `codex mcp-server` and `codex app-server` (#4471)
This is a very large PR with some non-backwards-compatible changes.
Historically, `codex mcp` (or `codex mcp serve`) started a JSON-RPC-ish
server that had two overlapping responsibilities:
- Running an MCP server, providing some basic tool calls.
- Running the app server used to power experiences such as the VS Code
extension.
This PR aims to separate these into distinct concepts:
- `codex mcp-server` for the MCP server
- `codex app-server` for the "application server"
Note `codex mcp` still exists because it already has its own subcommands
for MCP management (`list`, `add`, etc.)
The MCP logic continues to live in `codex-rs/mcp-server` whereas the
refactored app server logic is in the new `codex-rs/app-server` folder.
Note that most of the existing integration tests in
`codex-rs/mcp-server/tests/suite` were actually for the app server, so
all the tests have been moved with the exception of
`codex-rs/mcp-server/tests/suite/mod.rs`.
Because this is already a large diff, I tried not to change more than I
had to, so `codex-rs/app-server/tests/common/mcp_process.rs` still uses
the name `McpProcess` for now, but I will do some mechanical renamings
to things like `AppServer` in subsequent PRs.
While `mcp-server` and `app-server` share some overlapping functionality
(like reading streams of JSONL and dispatching based on message types)
and some differences (completely different message types), I ended up
doing a bit of copypasta between the two crates, as both have somewhat
similar `message_processor.rs` and `outgoing_message.rs` files for now,
though I expect them to diverge more in the near future.
One material change is that of the initialize handshake for `codex
app-server`, as we no longer use the MCP types for that handshake.
Instead, we update `codex-rs/protocol/src/mcp_protocol.rs` to add an
`Initialize` variant to `ClientRequest`, which takes the `ClientInfo`
object we need to update the `USER_AGENT_SUFFIX` in
`codex-rs/app-server/src/message_processor.rs`.
One other material change is in
`codex-rs/app-server/src/codex_message_processor.rs` where I eliminated
a use of the `send_event_as_notification()` method I am generally trying
to deprecate (because it blindly maps an `EventMsg` into a
`JSONNotification`) in favor of `send_server_notification()`, which
takes a `ServerNotification`, as that is intended to be a custom enum of
all notification types supported by the app server. So to make this
update, I had to introduce a new variant of `ServerNotification`,
`SessionConfigured`, which is a non-backwards compatible change with the
old `codex mcp`, and clients will have to be updated after the next
release that contains this PR. Note that
`codex-rs/app-server/tests/suite/list_resume.rs` also had to be update
to reflect this change.
I introduced `codex-rs/utils/json-to-toml/src/lib.rs` as a small utility
crate to avoid some of the copying between `mcp-server` and
`app-server`.
2025-09-30 00:06:18 -07:00
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
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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
fix: separate `codex mcp` into `codex mcp-server` and `codex app-server` (#4471)
This is a very large PR with some non-backwards-compatible changes.
Historically, `codex mcp` (or `codex mcp serve`) started a JSON-RPC-ish
server that had two overlapping responsibilities:
- Running an MCP server, providing some basic tool calls.
- Running the app server used to power experiences such as the VS Code
extension.
This PR aims to separate these into distinct concepts:
- `codex mcp-server` for the MCP server
- `codex app-server` for the "application server"
Note `codex mcp` still exists because it already has its own subcommands
for MCP management (`list`, `add`, etc.)
The MCP logic continues to live in `codex-rs/mcp-server` whereas the
refactored app server logic is in the new `codex-rs/app-server` folder.
Note that most of the existing integration tests in
`codex-rs/mcp-server/tests/suite` were actually for the app server, so
all the tests have been moved with the exception of
`codex-rs/mcp-server/tests/suite/mod.rs`.
Because this is already a large diff, I tried not to change more than I
had to, so `codex-rs/app-server/tests/common/mcp_process.rs` still uses
the name `McpProcess` for now, but I will do some mechanical renamings
to things like `AppServer` in subsequent PRs.
While `mcp-server` and `app-server` share some overlapping functionality
(like reading streams of JSONL and dispatching based on message types)
and some differences (completely different message types), I ended up
doing a bit of copypasta between the two crates, as both have somewhat
similar `message_processor.rs` and `outgoing_message.rs` files for now,
though I expect them to diverge more in the near future.
One material change is that of the initialize handshake for `codex
app-server`, as we no longer use the MCP types for that handshake.
Instead, we update `codex-rs/protocol/src/mcp_protocol.rs` to add an
`Initialize` variant to `ClientRequest`, which takes the `ClientInfo`
object we need to update the `USER_AGENT_SUFFIX` in
`codex-rs/app-server/src/message_processor.rs`.
One other material change is in
`codex-rs/app-server/src/codex_message_processor.rs` where I eliminated
a use of the `send_event_as_notification()` method I am generally trying
to deprecate (because it blindly maps an `EventMsg` into a
`JSONNotification`) in favor of `send_server_notification()`, which
takes a `ServerNotification`, as that is intended to be a custom enum of
all notification types supported by the app server. So to make this
update, I had to introduce a new variant of `ServerNotification`,
`SessionConfigured`, which is a non-backwards compatible change with the
old `codex mcp`, and clients will have to be updated after the next
release that contains this PR. Note that
`codex-rs/app-server/tests/suite/list_resume.rs` also had to be update
to reflect this change.
I introduced `codex-rs/utils/json-to-toml/src/lib.rs` as a small utility
crate to avoid some of the copying between `mcp-server` and
`app-server`.
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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:
**`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 |
| ----------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ |
| * * `prompt` ** (required) | string | The initial user prompt to start the Codex conversation. |
| `approval-policy` | string | Approval policy for shell commands generated by the model: `untrusted` , `on-failure` , `never` . |
| `base-instructions` | string | The set of instructions to use instead of the default ones. |
| `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` . |
| `cwd` | string | Working directory for the session. If relative, resolved against the server process's current directory. |
| `include-plan-tool` | boolean | Whether to include the plan tool in the conversation. |
| `model` | string | Optional override for the model name (e.g. `o3` , `o4-mini` ). |
| `profile` | string | Configuration profile from `config.toml` to specify default options. |
| `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 |
| ------------------------------- | ------ | -------------------------------------------------------- |
| * * `prompt` ** (required) | string | The next user prompt to continue the Codex conversation. |
| * * `conversationId` ** (required) | string | The id of the conversation to continue. |
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### Trying it Out
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README / docs refactor (#2724)
This PR cleans up the monolithic README by breaking it into a set
navigable pages under docs/ (install, getting started, configuration,
authentication, sandboxing and approvals, platform details, FAQ, ZDR,
contributing, license). The top‑level README is now more concise and
intuitive, (with corrected screenshots).
It also consolidates overlapping content from codex-rs/README.md into
the top‑level docs and updates links accordingly. The codex-rs README
remains in place for now as a pointer and for continuity.
Finally, added an extensive config reference table at the bottom of
docs/config.md.
---------
Co-authored-by: easong-openai <easong@openai.com>
2025-08-27 10:30:39 -07:00
> [!TIP]
2025-09-11 14:38:24 -07:00
> 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.
fix: separate `codex mcp` into `codex mcp-server` and `codex app-server` (#4471)
This is a very large PR with some non-backwards-compatible changes.
Historically, `codex mcp` (or `codex mcp serve`) started a JSON-RPC-ish
server that had two overlapping responsibilities:
- Running an MCP server, providing some basic tool calls.
- Running the app server used to power experiences such as the VS Code
extension.
This PR aims to separate these into distinct concepts:
- `codex mcp-server` for the MCP server
- `codex app-server` for the "application server"
Note `codex mcp` still exists because it already has its own subcommands
for MCP management (`list`, `add`, etc.)
The MCP logic continues to live in `codex-rs/mcp-server` whereas the
refactored app server logic is in the new `codex-rs/app-server` folder.
Note that most of the existing integration tests in
`codex-rs/mcp-server/tests/suite` were actually for the app server, so
all the tests have been moved with the exception of
`codex-rs/mcp-server/tests/suite/mod.rs`.
Because this is already a large diff, I tried not to change more than I
had to, so `codex-rs/app-server/tests/common/mcp_process.rs` still uses
the name `McpProcess` for now, but I will do some mechanical renamings
to things like `AppServer` in subsequent PRs.
While `mcp-server` and `app-server` share some overlapping functionality
(like reading streams of JSONL and dispatching based on message types)
and some differences (completely different message types), I ended up
doing a bit of copypasta between the two crates, as both have somewhat
similar `message_processor.rs` and `outgoing_message.rs` files for now,
though I expect them to diverge more in the near future.
One material change is that of the initialize handshake for `codex
app-server`, as we no longer use the MCP types for that handshake.
Instead, we update `codex-rs/protocol/src/mcp_protocol.rs` to add an
`Initialize` variant to `ClientRequest`, which takes the `ClientInfo`
object we need to update the `USER_AGENT_SUFFIX` in
`codex-rs/app-server/src/message_processor.rs`.
One other material change is in
`codex-rs/app-server/src/codex_message_processor.rs` where I eliminated
a use of the `send_event_as_notification()` method I am generally trying
to deprecate (because it blindly maps an `EventMsg` into a
`JSONNotification`) in favor of `send_server_notification()`, which
takes a `ServerNotification`, as that is intended to be a custom enum of
all notification types supported by the app server. So to make this
update, I had to introduce a new variant of `ServerNotification`,
`SessionConfigured`, which is a non-backwards compatible change with the
old `codex mcp`, and clients will have to be updated after the next
release that contains this PR. Note that
`codex-rs/app-server/tests/suite/list_resume.rs` also had to be update
to reflect this change.
I introduced `codex-rs/utils/json-to-toml/src/lib.rs` as a small utility
crate to avoid some of the copying between `mcp-server` and
`app-server`.
2025-09-30 00:06:18 -07:00
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
**prompt:** Implement a simple tic-tac-toe game with HTML, Javascript, and CSS. Write the game in a single file called index.html.
**sandbox:** workspace-write
Click "Run Tool" and you should see a list of events emitted from the Codex MCP server as it builds the game.
