AI agents call LLMs, invoke tools, and hit APIs — but have no built-in way to cap spend. A single agent loop can burn hundreds of dollars before anyone notices. Cycles MCP Server gives any MCP-compatible agent a runtime budget authority: tools to check, reserve, spend, and release budget before and after every costly operation. Works with Claude Desktop, Claude Code, Cursor, Windsurf, and any MCP host. Supports per-tenant budgets, soft-landing caps, and automatic heartbeat for long-running operations.