diff --git a/skills/codex/SKILL.md b/skills/codex/SKILL.md
index bb5698e..d2f5af7 100644
--- a/skills/codex/SKILL.md
+++ b/skills/codex/SKILL.md
@@ -37,6 +37,13 @@ Resume a session:
 uv run ~/.claude/skills/codex/scripts/codex.py resume <session_id> "<task>" [model] [working_dir]
 ```
 
+## Environment Variables
+
+- **CODEX_MODEL**: Override default model (default: `gpt-5.1-codex`)
+  - Example: `export CODEX_MODEL=gpt-5-codex`
+- **CODEX_TIMEOUT**: Override timeout in milliseconds (default: 7200000 = 2 hours)
+  - Example: `export CODEX_TIMEOUT=3600000` for 1 hour
+
 ## Timeout Control
 
 - **Built-in**: Script enforces 2-hour timeout by default
diff --git a/skills/codex/scripts/codex.py b/skills/codex/scripts/codex.py
index ada3c49..b09ccb9 100755
--- a/skills/codex/scripts/codex.py
+++ b/skills/codex/scripts/codex.py
@@ -19,7 +19,7 @@ import sys
 import os
 from typing import Optional
 
-DEFAULT_MODEL = 'gpt-5.1-codex'
+DEFAULT_MODEL = os.environ.get('CODEX_MODEL', 'gpt-5.1-codex')
 DEFAULT_WORKDIR = '.'
 DEFAULT_TIMEOUT = 7200  # 2 hours in seconds
 FORCE_KILL_DELAY = 5
diff --git a/skills/gemini/SKILL.md b/skills/gemini/SKILL.md
index 1896d40..128b809 100644
--- a/skills/gemini/SKILL.md
+++ b/skills/gemini/SKILL.md
@@ -30,6 +30,13 @@ uv run ~/.claude/skills/gemini/scripts/gemini.py -m <model> -p "<prompt>" [worki
 python3 ~/.claude/skills/gemini/scripts/gemini.py -m <model> -p "<prompt>" [working_dir]
 ```
 
+## Environment Variables
+
+- **GEMINI_MODEL**: Override default model (default: `gemini-3-pro-preview`)
+  - Example: `export GEMINI_MODEL=gemini-3`
+- **GEMINI_TIMEOUT**: Override timeout in milliseconds (default: 7200000 = 2 hours)
+  - Example: `export GEMINI_TIMEOUT=3600000` for 1 hour
+
 ## Timeout Control
 
 - **Built-in**: Script enforces 2-hour timeout by default
diff --git a/skills/gemini/scripts/gemini.py b/skills/gemini/scripts/gemini.py
index b2c647a..24991ec 100755
--- a/skills/gemini/scripts/gemini.py
+++ b/skills/gemini/scripts/gemini.py
@@ -16,7 +16,7 @@ import sys
 import os
 import argparse
 
-DEFAULT_MODEL = 'gemini-3-pro-preview'
+DEFAULT_MODEL = os.environ.get('GEMINI_MODEL', 'gemini-3-pro-preview')
 DEFAULT_WORKDIR = '.'
 DEFAULT_TIMEOUT = 7200  # 2 hours in seconds
 FORCE_KILL_DELAY = 5