Part 05 of the notebook
AGENTSAgents
Coding agents run for real: Claude Code, Codex, Gemini CLI and MCP, the errors they hit and the fix. Every agent error here was reproduced on a real install, with the agent's own version and logs, before it was written up.
press / and paste the message your agent printed.
- No.041
Fix: Claude Code "Prompt is too long"
Claude Code fails every message with Prompt is too long, or asks for usage credits. One oversized file did both in my tests, and Claude Code's guard missed it.
> Prompt is too long
AGENTS4 min - No.038
Fix: Claude Code "not compatible with the version of Windows"
Windows says claude.exe won't run right after an npm install of Claude Code. Your Windows is fine. Reproduced on npm 12, with the reinstall that fixed it.
> This version of C:\...\claude-code\bin\claude.exe is not compatible with the version of Windows you're running. Check your computer's system information and then contact the software publisher.
AGENTS3 min - No.037
Fix: Claude Code "Invalid API key" and "Please run /login"
A bad key can freeze Claude Code for 3 minutes before it errors. Every auth message reproduced, the Windows quoting trap, and what auth status hides.
> Invalid API key · Fix external API key
AGENTS4 min - No.033
Fix: Codex CLI error "stdin is not a terminal"
OpenAI's Codex CLI stops with stdin is not a terminal when it runs from a script, a pipe or CI. Why, and the command that works there, tested on 0.158.0.
> Error: stdin is not a terminal
AGENTS2 min - No.032
Fix: MCP error -32000 Connection closed / Failed to connect
An MCP server fails with Connection closed or Failed to connect and never says why. Where the real error is hiding, and the fixes, tested in Claude Code.
> MCP error -32000: Connection closed
AGENTS3 min
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