Fetches content from a URL and returns it in the requested format.

Usage:
- Provide a full URL starting with http:// or https://
- The format parameter controls output: "markdown" (default) converts HTML to readable markdown, "text" strips all HTML tags, "html" returns the raw HTML
- Default timeout is 30 seconds; maximum is 120 seconds
- Responses larger than 5MB are rejected
- Use markdown format for reading documentation, articles, or web pages
- Use html format only when you need the raw HTML structure
- Use text format when you need plain text without any markup
