Code Quality Tool

Code Complexity Analyzer

Calculate cyclomatic complexity, cognitive complexity, Halstead metrics, and maintainability index for any codebase.

Install

Get the CLI Tool

Run the complexity analyzer locally as an MCP server, or try it online below.

npx @clinetools/complexity
Requires Node.js 18+
  • 4 metrics — Cyclomatic, Cognitive, Halstead, Maintainability Index
  • Per-function breakdowns with risk ratings
  • Directory scanning — analyze entire projects
  • JS/TS, Python, Go, Rust, Java, C/C++ support
  • Zero config — just run with npx
Tutorial

How to Use It

Three ways to analyze code complexity — pick the one that fits your workflow.

1

Try Online

Use the interactive demo below to paste code and analyze complexity — no install needed.

↓ Jump to interactive demo
2

Use via CLI

Run as a local MCP server and connect any MCP-compatible client.

npx @clinetools/complexity
3

Add to Cline / Claude Code

Add the tool to your MCP settings for instant access from your AI assistant.

"code-complexity": { "command": "npx", "args": ["@clinetools/complexity"] }

MCP Client Configuration (Cline) 

{
  "mcpServers": {
    "code-complexity": {
      "command": "npx",
      "args": ["@clinetools/complexity"]
    }
  }
}

Claude Code Configuration 

# In your project's .mcp.json:
{
  "mcpServers": {
    "code-complexity": {
      "command": "npx",
      "args": ["@clinetools/complexity"]
    }
  }
}

Example Prompt: Analyze a Directory 

// Prompt to your AI agent:
"Analyze the complexity of src/ and flag any
function with cyclomatic complexity over 15"

// The agent calls:
analyze_complexity({
  path: "src/",
  metrics: ["cyclomatic", "cognitive"]
})

Example Prompt: Find the Most Complex Function 

// Prompt to your AI agent:
"Find the most complex function in this project
and suggest how to simplify it"

// The agent calls:
analyze_complexity({
  path: ".",
  metrics: ["all"]
})
// Then reads the hotspots list and offers refactoring advice
Live Demo

Try It Online

Paste code below and analyze its complexity with 4 industry-standard metrics.

Paste Code to Analyze

JavaScript, TypeScript, or Python source code

Try a demo:

Paste code and click Analyze Complexity to see metrics.

Per-Function Breakdown

FunctionCCCogLinesRisk
Reference

Understanding Complexity Metrics

What each metric measures and why it matters for code quality.

Cyclomatic Complexity

Counts independent paths through code: if, for, while, case, catch, &&, ||, ternary. Target: ≤10 per function. Created by Thomas McCabe in 1976.

Cognitive Complexity

Measures how hard code is to understand. Like cyclomatic but penalizes nesting: a nested if inside a for scores higher. Target: ≤15. Created by SonarSource.

Halstead Metrics

Counts operators and operands to estimate Volume (program size), Difficulty, Effort (time to write), and predicted Bugs. Created by Maurice Halstead in 1977.

Maintainability Index

Composite score (0-100) combining Halstead Volume, Cyclomatic Complexity, Lines of Code, and Comment Ratio. Grade A (≥80) to F (<20). Target: ≥60.

Need Automated Quality Gates?

Our Pro plan includes CI/CD complexity checks that block merges when thresholds are exceeded.

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