diff --git a/docs/config.md b/docs/config.md
index df4da3b005..a3e6ed266b 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -195,6 +195,7 @@ If the selected model is known to support reasoning (for example: `o3`, `o4-mini
 - `"low"`
 - `"medium"` (default)
 - `"high"`
+- `"xhigh"` (available only on `gpt-5.1-codex-max`)
 
 Note: to minimize reasoning, choose `"minimal"`.
 
diff --git a/docs/example-config.md b/docs/example-config.md
index bd220a41e6..cc53efa612 100644
--- a/docs/example-config.md
+++ b/docs/example-config.md
@@ -37,7 +37,7 @@ model_provider = "openai"
 # Reasoning & Verbosity (Responses API capable models)
 ################################################################################
 
-# Reasoning effort: minimal | low | medium | high (default: medium)
+# Reasoning effort: minimal | low | medium | high | xhigh (default: medium; xhigh only on gpt-5.1-codex-max)
 model_reasoning_effort = "medium"
 
 # Reasoning summary: auto | concise | detailed | none (default: auto)
diff --git a/docs/faq.md b/docs/faq.md
index 72cbdff792..37b9ef39d8 100644
--- a/docs/faq.md
+++ b/docs/faq.md
@@ -8,7 +8,7 @@ In 2021, OpenAI released Codex, an AI system designed to generate code from natu
 
 ### Which models are supported?
 
-We recommend using Codex with GPT-5.1 Codex, our best coding model. The default reasoning level is medium, and you can upgrade to high for complex tasks with the `/model` command.
+We recommend using Codex with GPT-5.1 Codex Max, our best coding model. The default reasoning level is medium, and you can upgrade to high or xhigh (Codex Max only) for complex tasks with the `/model` command.
 
 You can also use older models by using API-based auth and launching codex with the `--model` flag.