docs: fix Codex MCP add instructions

Author: root

README.md

@@ -143,12 +143,23 @@ claude mcp add chrome-devtools --scope user npx chrome-devtools-mcp@latest
   using the standard config from above. You can also install the Chrome DevTools MCP server using the Codex CLI:
 
 ```bash
-codex mcp add chrome-devtools -- npx chrome-devtools-mcp@latest
+codex mcp add chrome-devtools -- npx -y chrome-devtools-mcp@latest
+```
+
+Verification: run `codex mcp list` and confirm `chrome-devtools` is listed.
+
+If you see `error: unexpected argument 'add' found`, your Codex CLI is too old to support `codex mcp add`.
+Upgrade Codex, or add the server manually by editing `~/.codex/config.toml`:
+
+```toml
+[mcp_servers.chrome-devtools]
+command = "npx"
+args = ["-y", "chrome-devtools-mcp@latest"]
 ```
 
 **On Windows 11**
 
-Configure the Chrome install location and increase the startup timeout by updating `.codex/config.toml` and adding the following `env` and `startup_timeout_ms` parameters:
+Configure the Chrome install location and increase the startup timeout by updating `%USERPROFILE%\.codex\config.toml` (usually `C:\Users\<you>\.codex\config.toml`) and adding the following `env` and `startup_timeout_ms` parameters:
 
 ```
 [mcp_servers.chrome-devtools]

docs/troubleshooting.md

@@ -38,6 +38,19 @@ Using `.mcp.json` to debug while using a client:
 
 ## Specific problems
 
+### Codex: `error: unexpected argument 'add' found`
+
+Some older Codex CLI versions don't include the `codex mcp add`/`list` subcommands.
+
+- Run `codex mcp --help` and check whether it shows `add`.
+- If it does not, upgrade Codex, or add the server manually by editing `~/.codex/config.toml`:
+
+```toml
+[mcp_servers.chrome-devtools]
+command = "npx"
+args = ["-y", "chrome-devtools-mcp@latest"]
+```
+
 ### `Error [ERR_MODULE_NOT_FOUND]: Cannot find module ...`
 
 This usually indicates either a non-supported Node version is in use or that the