The correct answer is /context when the requirement is to verify the current token usage of the active context window. GitHub documents /context as the command that displays the active model and the number of tokens currently in use relative to the model's total context capacity. It also provides a breakdown across the system prompt, custom instructions, built-in tools, MCP tools, conversation messages, free space, and reserved buffer.
This is distinct from /usage. /usage reports broader session statistics, including AI Credits consumed, session duration, lines edited, and per-model token totals. Therefore, /usage is appropriate when reviewing cumulative session consumption, but /context is the more precise answer to a question asking for the current token usage of the working context.
/compact reduces context pressure by summarizing earlier conversation history; it does not merely report the current token state. /diff reviews code changes and is unrelated to context or token accounting.
Study Guide Reference Topics: Manage Memory, State, and Execution; context-window monitoring; token-budget management; maintaining effective long-running agent sessions.