Agent Client Protocol separates an application's interface from the agent doing the work. Compatible clients and agents can exchange structured messages rather than requiring a different custom integration for every pairing.
Connections establish supported capabilities, and sessions organize user prompts and agent updates. JSON-RPC provides the message format. Actual compatibility still depends on the features and protocol versions each implementation supports.
ELI5
Agent Client Protocol is a shared communication method between a development application and a coding agent. It gives both sides an agreed way to exchange requests, progress, results, and other task information.
For example, an editor can use the protocol to host a Claude Code session without rebuilding the entire connection from scratch. The application must still control permissions and show users what the connected agent is doing.
