diff --git a/docs/installation-guides/install-codex.md b/docs/installation-guides/install-codex.md
index 5f92996bc2..184e150f0d 100644
--- a/docs/installation-guides/install-codex.md
+++ b/docs/installation-guides/install-codex.md
@@ -21,9 +21,11 @@ bearer_token_env_var = "GITHUB_PAT_TOKEN"
 You can also add it via the Codex CLI:
 
 ```cli
-codex mcp add github --url https://api.githubcopilot.com/mcp/  
+codex mcp add github --url https://api.githubcopilot.com/mcp/ --bearer-token-env-var GITHUB_PAT_TOKEN
 ```
 
+Using `codex mcp add ... --url ...` without `--bearer-token-env-var` only stores the remote server URL. For the hosted GitHub MCP server, you also need to bind a PAT environment variable so Codex can send the `Authorization` header.
+
 <details>
 <summary><b>Storing Your PAT Securely</b></summary>
 <br>