Context

/context shows tokens consumed in the current session and available tokens, broken down by category.

Example (new session): claude-sonnet-4-6 · 0k/200k tokens (0%). Estimated usage by category:

Skills: 237 tokens (0.1%)
Free space: 167k (83.4%)
Autocompact buffer: 33k tokens (16.5%)

Example (older session): 17k/200k tokens (9%). Categories: System prompt, System tools, Skills, Messages, Free space, Autocompact buffer.

Also lists MCP tools (/mcp, loaded on-demand, with available tools), Memory files (/memory, e.g. CLAUDE.md), and Skills (/skills).

Auto-compact buffer in Claude Code is a reserved portion of the model's context window (e.g. 33k-45k tokens, ~16.5-22.5%) that ensures there is enough headroom to summarize conversation history when limits are approached.

Using /resume or claude --resume lets you choose a previous session.