CRASH (Cascaded Reasoning with Adaptive Step Handling) is an MCP server designed for structured, iterative reasoning in complex problem solving and analysis. Built as a backward-compatible evolution of the MCP Sequential Thinking Server, CRASH emphasizes token-efficiency and streamlined prompts: it avoids embedding codes in thoughts and does not require agents to enumerate tools. In CRASH v2.0, the server adds flexible validation, explicit confidence tracking, a revision mechanism, and native branching so users can explore multiple solution paths in parallel. It supports a broad set of purpose types (including validation, exploration, hypothesis, correction, planning) and allows custom purposes when not in strict mode. The architecture enables natural language flow, configurable formatting, and structured actions that integrate with tools, with multiple output formats (console, JSON, Markdown). Session management allows multiple concurrent reasoning chains with unique IDs. Environment variables control behavior (e.g., MAX_HISTORY_SIZE, CRASH_STRICT_MODE, CRASH_OUTPUT_FORMAT). The system is installable via npm and portable across editors like Cursor, Claude Code, Windsurf, and VS Code, making MCP-enabled workflows more flexible and scalable.