The most compatible MCP CLI client. Supports: tools, resources, prompts, completions, async tasks, skills, stdio and streamable HTTP (MCP 2026-07-28 and 2025-11-25), persistent sessions, OAuth 2.1 with DCR, CIMD, client credentials, and ID-JAG, OS keychain, --json for code mode, grep for tool discovery, proxy for AI sandboxes, x402, and more.