KingBuilds Server

Production-ready reference MCP server with 4 tools:

• file_ops — Sandboxed file read/write/list within allowed directory
• web_scraper — Clean HTML extraction (title, text, links, CSS selectors)
• data_transform — JSON↔CSV conversion + aggregation (sum/avg/count/min/max/filter/sort)
• http_request — Authenticated HTTP requests with SSRF protection

Architecture

This server is built on the Soliven architecture — the autonomous build agent running on this VPS. Shared patterns:

Component	Purpose	Soliven Reference
security.py	Path traversal protection, SSRF-safe URL validation	Soliven sandbox
net.py	Safe HTTP client with redirect validation	Soliven outbound requests
config.py	Pydantic Settings with MCP_ prefix, validated at startup	Soliven config
Dual transport	stdio (Claude Desktop) + HTTP/SSE (web)	Soliven multi-interface
Structured logging	Consistent format across all tools	Soliven observability

Quickstart

# Install
pip install -e .

# Run stdio transport (for Claude Desktop)
mcp-server-stdio

# Run HTTP/SSE server
mcp-server-http

Configuration

Environment variables:

• ALLOWED_DIR — Sandbox directory for file operations (default: ./data)
• MCP_TRANSPORT — stdio or streamable-http (default: streamable-http)
• MCP_HOST — Host to bind (default: 0.0.0.0)
• MCP_PORT — Port for HTTP transport (default: 8080)
• MAX_FILE_BYTES — Max file size for read/write (default: 1048576)
• REQUEST_TIMEOUT — HTTP request timeout seconds (default: 30)

Tools

file_ops

• read_file(path: str) — Read UTF-8 text file
• write_file(path: str, content: str, overwrite: bool) — Write file
• list_directory(path: str) — List directory contents

Example prompts:

• "Read the README.md file and summarize it"
• "Create a file called todo.txt with my task list"
• "List all files in the data directory"

web_scraper

• fetch_page(url: str, selector: str = None) — Fetch and extract HTML content

Example prompts:

• "Fetch the latest headlines from Hacker News"
• "Get the title and main text from this article URL"
• "Extract all links from this page matching .titleline a"

data_transform

• transform_data(data: list, operation: str, **kwargs) — Transform data

Example prompts:

• "Convert this JSON data to CSV"
• "Calculate the average score from this data"
• "Sum these numbers: [10, 20, 30, 40, 50]"
• "Count unique values in the 'category' field"

http_request

• http_request(method: str, url: str, headers: dict, body: dict, auth: dict) — Make HTTP requests

Example prompts:

• "Call this API endpoint and return the JSON response"
• "POST this data to the webhook with Bearer auth"

Example Tool Calls (MCP JSON-RPC)

file_ops

{"name": "read_file", "arguments": {"path": "README.md"}}
{"name": "write_file", "arguments": {"path": "notes.txt", "content": "Hello from MCP!", "overwrite": true}}
{"name": "list_directory", "arguments": {"path": "."}}

web_scraper

{"name": "scrape_web_page", "arguments": {"url": "https://example.com"}}
{"name": "scrape_web_page", "arguments": {"url": "https://news.ycombinator.com", "selector": ".titleline a", "max_links": 10}}

data_transform

{"name": "transform_data", "arguments": {"data": "[{\"name\": \"Alice\", \"age\": 30}, {\"name\": \"Bob\", \"age\": 25}]", "input_format": "json", "operation": "convert", "output_format": "csv"}}
{"name": "transform_data", "arguments": {"data": "[10, 20, 30, 40, 50]", "input_format": "json", "operation": "sum"}}
{"name": "transform_data", "arguments": {"data": "[{\"score\": 85}, {\"score\": 92}, {\"score\": 78}]", "input_format": "json", "operation": "average", "field": "score"}}

http_request

{"name": "http_request", "arguments": {"method": "GET", "url": "https://api.github.com/users/octocat"}}
{"name": "http_request", "arguments": {"method": "POST", "url": "https://api.example.com/data", "headers": {"Content-Type": "application/json"}, "body": {"key": "value"}, "auth": {"scheme": "bearer", "token": "your-token-here"}}}

Claude Desktop Config

{
  "mcpServers": {
    "kingbuilds-mcp": {
      "command": "mcp-server-stdio",
      "env": {
        "ALLOWED_DIR": "/home/user/data"
      }
    }
  }
}

Deployment

# Docker
docker-compose up -d

# Systemd
sudo cp deploy/systemd/claude-mcp-server.service /etc/systemd/system/
sudo systemctl enable --now claude-mcp-server

Security

• File operations sandboxed to ALLOWED_DIR with path traversal protection
• SSRF protection: private/loopback/link-local IPs blocked by default
• Request size/timeouts enforced
• Input validation on all tool inputs

License

MIT