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CRASH

Community
An MCP server for structured, iterative reasoning with step tracking, branching, and revisions.
How to install ↓ Compare GitHub source repository ↗
Category
Dev Tools #121 of 438
Stars
★ 72 Popular
Transport
stdio (local process)
Runtime
Node.js 18+ · Docker · Bun · Deno
Credentials
No credential needed
License
MIT
Last commit
⚠
Tools
1
60FMRS · C

CRASH provides a valuable tool for structured reasoning, especially for complex problems. It is more concise than sequential thinking but may not be needed for simple tasks.

Strongest · Documentation 15/20 Weakest · Security and permissions 8/20

Reliability
10/20
Security and permissions
8/20
Maintenance
14/20
Documentation
15/20
Setup experience
13/20
Why each score
Reliability 10/20
Source inspection shows clear server entry and tool registration, with reasonable build config, but no automated tests or CI evidence to verify startup and actual behavior. Deducted for missing execution evidence, so not above 12.
Security and permissions 8/20
The server processes no sensitive credentials, performs only local in-memory operations with no network access, low risk. However, no security audit or data-flow disclosure is provided, and no confirmation mechanism for potentially dangerous operations, but due to its limited use, a moderately high score is given.
Maintenance 14/20
Repository has MIT license, moderate activity with recent commits, but release/versioning details not fully clear, no security response channel, hence deduction.
Documentation 15/20
README provides extensive install, config, parameter docs and examples, but lacks deep troubleshooting and cost details. Overall documentation quality is good.
Setup experience 13/20
Install and config steps are clear with client config examples, supporting npx, Docker, Bun. However, lacks test/CI evidence for successful setup, and possible platform issues not fully covered, so score below 15.

Static review · not runListed 2026-08-07

Read the FMRS scoring method →

Fit and risk

Best for

  • Complex tasks that require structured reasoning
  • Scenarios needing step validation and revisions
  • Exploring multiple solution paths

Not for

  • Simple single-step tasks
  • Pure information retrieval
  • Deterministic procedures with no uncertainty

Required permissions

  • Network access to fetch package via npx
  • File system access for config files (client-dependent)

Risks and side effects

  • Package may be unvetted (community project)
  • Misconfiguration can cause startup failures
  • Environment variables not set correctly may lead to unexpected behavior

Setup

Before you start

Runtime：Node.js 18+ · Docker · Bun · Deno

Other optional settings (7)
CRASH_STRICT_MODE optional Enables strict validation (requires specific prefixes); defaults to false.
MAX_HISTORY_SIZE optional Maximum steps retained in history; defaults to 100.
CRASH_OUTPUT_FORMAT optional Output format: console, , or markdown; defaults to console.
CRASH_NO_COLOR optional Set to true to disable colored console output.
CRASH_SESSION_TIMEOUT optional Session timeout in minutes; defaults to 60.
CRASH_MAX_BRANCH_DEPTH optional Maximum branch nesting depth; defaults to 5.
CRASH_ENABLE_SESSIONS optional Whether to enable session management; defaults to false.

Install via npm: npm install crash-mcp. Or run directly with npx: npx crash-mcp. For most MCP clients, add the JSON config: {"mcpServers":{"crash":{"command":"npx","args":["-y","crash-mcp"]}}}. See README for client-specific setup.

claude_desktop_config.json 
{
  "mcpServers": {
    "crash": {
      "command": "npx",
      "args": [
        "-y",
        "crash-mcp"
      ]
    }
  }
}

Shown for Claude Desktop. Other clients may use a different file or key (VS Code uses "servers") — the configurator below converts it.

.vscode/mcp.json
{
  "servers": {
    "crash": {
      "command": "npx",
      "args": [
        "-y",
        "crash-mcp"
      ]
    }
  }
}

Goes in your project's .vscode/mcp.json (VS Code uses a "servers" key).

Terminal
claude mcp add crash -- npx -y crash-mcp

Run it in a terminal; replace any <…> placeholders with your own values first.

Generate and validate client config

Check that it works

After connecting the client, check the tool list for a tool named handle_step; then prompt "use crash to analyze a complex problem step by step" and confirm it returns structured, step-numbered reasoning output.

Troubleshooting

  1. Module not found errors: try using bunx instead of npx
  2. ESM resolution issues: try --node-options=--experimental-vm-modules flag
  3. Check environment variables like CRASH_STRICT_MODE and CRASH_OUTPUT_FORMAT are set correctly

Things to try

Once connected, you can ask your AI assistant things like:

  • Use crash to break down why my database queries are slow and propose optimizations step by step.
  • Use crash to explore two different caching strategies and compare their trade-offs.
  • Use crash to debug this error systematically, with a confidence score at each step.
  • Use crash to revise step 2 of your analysis since it missed a join condition.

Tools 1

handle_step writes
Processes a single reasoning step with parameters like step number, purpose, thought, outcome, next action, and rationale, plus optional confidence, revision, branching, and dependencies.

Use cases

Complex multi-step problem solving
Code analysis and optimization
System design with multiple considerations
Debugging requiring systematic investigation
Exploring multiple solution paths
Tasks where you need to track confidence

Supported clients

Claude Desktop
Claude Code
Cursor
VS Code
Windsurf
JetBrains IDEs

Listed from the project's documentation, not tested by this site.

Overview

CRASH (Cascaded Reasoning with Adaptive Step Handling) is an MCP server for structured, iterative reasoning. It helps AI assistants break down complex problems into trackable steps with confidence tracking, revision support, and branching for exploring alternatives. Inspired by the MCP Sequential Thinking Server, it is more token-efficient and streamlined.

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Source revision b74f5ce91e21 Data synced 2026-10-19 Read the FMRS scoring method