Claude Code

How it works · 11 min read

Why the agent stopped before it finished

You asked for five things and got one, with a confident summary and no error. An agent loop ends when the model writes a message containing no tool call — a judgement nothing checks against your task. The five ways a run ends early, each fingerprint, and the phrasing that fixes it.

How it works · 11 min read

Where you edit your prompt decides what it costs

The session was fast for twenty turns, then you added one line to the top of a file and the next answer crawled. A prompt cache is keyed on an exact prefix, so cost and latency depend on where you changed something, not how much. The ordering rule that falls out of it.

Troubleshooting · 9 min read

Your MCP server connects and the tools still do not run

The server is green, the tool count is right, and the model answers without touching any of it. That is a selection problem, not a connection problem: ten causes with distinct fingerprints, from a six-word description to the thirtieth tool that pushed the right one out of reach.