Context Usage Breakdown

Not sure if this will land in the docs, but happy to explain here:

Bucket What’s in it Your control
System prompt Cursor’s built-in instructions to the model (how to behave, how to call tools, formatting) None
Tools The list of tools the model can use and how to call them Mode (Ask / Plan / Agent etc.) sets the core toolset. A few extras like Web Search and Web Fetch can be toggled in Settings. Core tools (Read, Edit, Grep, Shell, Task…) can’t be turned off
Rules Workspace and user rules that load at the start of the chat. Agent-requestable rules contribute only their description here; the body counts as Conversation if/when the agent reads it Trim always-on rules; prefer agent-requestable rules with tight descriptions
Skills The catalog of available skills (names + descriptions + paths) loaded at the start. A skill’s body only counts once the agent opens it Same idea as Rules — fewer/tighter skill entries
MCP Everything your MCP servers inject up front: their instructions and the list of tools/resources they expose. MCP tool results don’t count here, those go to Conversation Disable MCP servers/tools you don’t need for this chat
Subagents Descriptions of the subagent types you can delegate to Register fewer subagents
Summarized conversation When the chat gets long, Cursor compresses earlier turns into a summary, which lives here Automatic or via /summarize
Conversation Everything else: your messages, the agent’s replies and thinking, tool calls and their results, file contents it read, search results, images Start a new chat, or let it summarize