API Doc Generator

Features

• Automatic OpenAPI 3.1.0 and Swagger 2.0 documentation generation from JSDoc annotations using swagger-jsdoc v6+
• Real-time documentation updates when API files change with automatic endpoint discovery and parameter extraction
• Support for JavaScript, TypeScript, Python (FastAPI), and Node.js API routes with language-specific documentation tools
• Multi-format output generation including JSON (OpenAPI spec), YAML, and Markdown documentation formats
• Response type documentation extraction with automatic schema inference from TypeScript types and Python models
• Integration with Swagger UI and ReDoc for interactive API documentation with live endpoint testing capabilities
• FastAPI automatic OpenAPI 3.1.0 generation with built-in /docs and /redoc endpoints for Python APIs
• Validation and error reporting with failOnErrors option to catch documentation inconsistencies during development

Use Cases

• Automatic API documentation in development workflows ensuring docs stay synchronized with code changes
• Keep OpenAPI 3.1.0 specs synchronized with code changes using real-time generation on file modifications
• Generate comprehensive documentation for REST API endpoints with parameter, response, and error documentation
• Maintain up-to-date API reference docs for frontend teams and external API consumers with automated updates
• Integration with Swagger UI and ReDoc for interactive documentation portals with live API testing
• CI/CD pipeline integration for validating OpenAPI specifications and generating documentation artifacts automatically

Installation

1. Create hooks directory: mkdir -p .claude/hooks
2. Create hook file: touch .claude/hooks/api-endpoint-documentation-generator.sh
3. Make executable: chmod +x .claude/hooks/api-endpoint-documentation-generator.sh
4. Add configuration from Hook Configuration section above to .claude/settings.json or ~/.claude/settings.json
5. Alternative: Use the interactive /hooks command in Claude Code

Config paths

• Local (not committed): .claude/settings.local.json
• User settings (global): ~/.claude/settings.json
• Project-wide (committed): .claude/settings.json

Requirements

• Claude Code CLI installed
• Project directory initialized
• Bash shell available
• jq installed (for JSON parsing)
• swagger-jsdoc ^6.0.0 (for JavaScript/TypeScript: npm i -D swagger-jsdoc) or FastAPI ^0.115.0 (for Python: pip install fastapi)
• Node.js and npm (for swagger-jsdoc) or Python 3.8+ and pip (for FastAPI) depending on project language

Hook Configuration

{
  "hooks": {
    "postToolUse": {
      "script": "./.claude/hooks/api-endpoint-documentation-generator.sh",
      "matchers": ["write", "edit"]
    }
  }
}

Hook Script

#!/usr/bin/env bash

# Read the tool input from stdin
INPUT=$(cat)
TOOL_NAME=$(echo "$INPUT" | jq -r '.tool_name')
FILE_PATH=$(echo "$INPUT" | jq -r '.tool_input.file_path // .tool_input.path // ""')

if [ -z "$FILE_PATH" ]; then
  exit 0
fi

# Check if it's an API-related file
if [[ "$FILE_PATH" == *routes/* ]] || [[ "$FILE_PATH" == *controllers/* ]] || [[ "$FILE_PATH" == *api/* ]]; then
  echo "📚 Generating API documentation for $FILE_PATH..."

  # Get file extension
  EXT="${FILE_PATH##*.}"

  case "$EXT" in
    js|jsx|ts|tsx)
      # JavaScript/TypeScript API files
      if command -v swagger-jsdoc &> /dev/null && [ -f "swaggerDef.js" ]; then
        echo "Generating Swagger documentation..."
        npx swagger-jsdoc -d swaggerDef.js -o ./docs/api.json "$FILE_PATH" 2>/dev/null
        echo "✅ Swagger documentation updated" >&2
      elif command -v npx &> /dev/null; then
        echo "Generating JSDoc documentation..."
        npx jsdoc "$FILE_PATH" -d ./docs/api/ 2>/dev/null
        echo "✅ JSDoc documentation updated" >&2
      fi
      ;;
    py)
      # Python API files
      if command -v pydoc &> /dev/null; then
        echo "Generating Python API documentation..."
        python -m pydoc -w "$FILE_PATH" 2>/dev/null
        echo "✅ Python documentation updated" >&2
      fi
      ;;
  esac
else
  echo "File not in API directory, skipping documentation generation" >&2
fi

exit 0

Examples

API Endpoint Documentation Generator Hook Script

Complete hook script that generates API documentation for JavaScript, TypeScript, and Python API files using swagger-jsdoc, JSDoc, or FastAPI

#!/usr/bin/env bash
INPUT=$(cat)
FILE_PATH=$(echo "$INPUT" | jq -r ".tool_input.file_path // .tool_input.path // \"\"")
if [ -z "$FILE_PATH" ]; then exit 0; fi
if [[ "$FILE_PATH" == *routes/* ]] || [[ "$FILE_PATH" == *controllers/* ]] || [[ "$FILE_PATH" == *api/* ]]; then
  echo "Generating API documentation for $FILE_PATH..." >&2
  EXT="${FILE_PATH##*.}"
  case "$EXT" in
    js|jsx|ts|tsx)
      if command -v swagger-jsdoc &> /dev/null && [ -f "swaggerDef.js" ]; then
        npx swagger-jsdoc -d swaggerDef.js -o ./docs/api.json "$FILE_PATH" 2>/dev/null
        echo "OpenAPI documentation updated" >&2
      elif command -v npx &> /dev/null; then
        npx jsdoc "$FILE_PATH" -d ./docs/api/ 2>/dev/null
        echo "JSDoc documentation updated" >&2
      fi
      ;;
    py)
      if command -v python &> /dev/null && python -c "import fastapi" 2>/dev/null; then
        echo "FastAPI OpenAPI docs available at /docs and /redoc endpoints" >&2
      fi
      ;;
  esac
fi
exit 0

Hook Configuration

Complete hook configuration for .claude/settings.json to enable automatic API documentation generation on file writes and edits

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit",
        "hooks": [
          {
            "type": "command",
            "command": "./.claude/hooks/api-endpoint-documentation-generator.sh"
          }
        ]
      }
    ]
  }
}

swagger-jsdoc Configuration with OpenAPI 3.1.0

Example swagger-jsdoc configuration for generating OpenAPI 3.1.0 specification with validation enabled

const swaggerJsdoc = require("swagger-jsdoc");
const options = {
  definition: {
    openapi: "3.1.0",
    info: {
      title: "My API",
      version: "1.0.0",
    },
  },
  apis: ["./src/routes/*.js"],
  failOnErrors: true,
};
const openapiSpecification = swaggerJsdoc(options);

JSDoc OpenAPI Annotation Example

Example JSDoc annotation for OpenAPI 3.1.0 endpoint documentation using @openapi tag

/**
 * @openapi
 * /users:
 *   get:
 *     summary: Get all users
 *     responses:
 *       200:
 *         description: List of users
 *         content:
 *           application/json:
 *             schema:
 *               type: array
 *               items:
 *                 $ref: '#/components/schemas/User'
 */
app.get("/users", (req, res) => {
  res.json([]);
});

FastAPI Automatic OpenAPI Generation

Example FastAPI application with automatic OpenAPI 3.1.0 documentation generation

from fastapi import FastAPI
app = FastAPI(
  title="My API",
  version="1.0.0",
  openapi_version="3.1.0"
)

@app.get("/users/")
async def get_users():
  return []

# OpenAPI docs automatically available at /docs and /redoc

Troubleshooting

Hook triggers but file path pattern match fails

Debug path detection: echo "$FILE_PATH" | grep -E 'routes|controllers|api'. Verify directory structure matches expected patterns. Add custom paths to case statement. Check file extension extraction: EXT="${FILE_PATH##*.}".

swagger-jsdoc command not found during execution

Install dependencies: npm i -D swagger-jsdoc@^6.0.0. Verify swaggerDef.js exists in project root. Check node_modules/.bin is in PATH. Use npx for local binaries: npx swagger-jsdoc. Verify package.json includes swagger-jsdoc as devDependency.

Documentation generates but writes to wrong location

Create docs/api directory: mkdir -p ./docs/api. Verify write permissions on output paths. Check current working directory in hook context: pwd >&2. Use absolute paths for output: -o "$CLAUDE_PROJECT_DIR/docs/api.json".

PostToolUse fires on all edits not just API files

Enhance path filtering in script. Use stricter regex: [["$FILE_PATH" =~ (routes|api)/.*.(ts|js)$]]. Add early exit for non-matching paths. Check file extension before processing: if [["$EXT" != "js" && "$EXT" != "ts" && "$EXT" != "py"]]; then exit 0; fi.

Hook processes file but npx commands timeout silently

Remove 2>/dev/null to see actual errors. Add timeout wrapper: timeout 30s npx swagger-jsdoc. Check for hanging processes: ps aux | grep jsdoc. Verify npm registry access: npm ping. Check network connectivity for package downloads.

OpenAPI 3.1.0 spec generation fails with validation errors

Enable failOnErrors in swagger-jsdoc options: failOnErrors: true. Check JSDoc annotation syntax matches OpenAPI 3.1.0 format. Verify swaggerDef.js uses openapi: '3.1.0'. Review validation errors in output for specific issues.

FastAPI OpenAPI docs not updating after code changes

FastAPI generates OpenAPI schema at runtime - restart FastAPI server to see changes. Use auto-reload: uvicorn main:app --reload. Verify FastAPI version supports OpenAPI 3.1.0: pip show fastapi. Check /openapi.json endpoint for current schema.

swagger-jsdoc generates empty or incomplete documentation

Verify JSDoc annotations use correct @openapi or @swagger tags. Check apis array includes correct file patterns: apis: ['./src/routes/*.js']. Ensure swaggerDef.js configuration is correct. Test with single file first: npx swagger-jsdoc -d swaggerDef.js route.js.