tool_monitor_changes

Monitor web page changes by comparing content hashes to detect modifications over time, providing change detection reports for tracking updates.

Instructions

Check if a page has changed.

Tracks content modifications over time.

Args: url: URL to monitor. previous_hash: Previous content hash to compare against.

Returns: Change detection report with content hash.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`url`	Yes
`previous_hash`	No

Implementation Reference

src/devlens/tools/advanced.py:226-270 (handler)

The actual implementation of the monitor_changes logic, which fetches the page and performs content comparison.

async def monitor_changes(url: str, previous_content: str | None = None) -> str:
    """Check if a page has changed since last check.

    Args:
        url: URL to monitor.
        previous_content: Previous content hash or snippet to compare.

    Returns:
        Change detection report.

    Example:
        >>> changes = await monitor_changes("https://example.com", previous_hash)
    """
    try:
        doc = await _scraper.fetch(url, retry=1)
        current_content = doc.content

        # Generate content hash
        import hashlib

        current_hash = hashlib.sha256(current_content.encode()).hexdigest()[:16]

        report_lines = [
            f"# Change Monitor: {doc.title}\n",
            f"> URL: {url}\n",
            f"> Checked: {doc.fetched_at.strftime('%Y-%m-%d %H:%M:%S')}\n",
            "\n## Status\n",
        ]

        if previous_content:
            if previous_content == current_hash:
                report_lines.append("✓ **No changes detected**\n")
            else:
                report_lines.append("⚠️ **Content has changed**\n")
                report_lines.append(f"\n- Previous hash: `{previous_content}`\n")
                report_lines.append(f"- Current hash: `{current_hash}`\n")
        else:
            report_lines.append("ℹ️ **First check - baseline established**\n")
            report_lines.append(f"\n- Content hash: `{current_hash}`\n")

        # Add content preview
        report_lines.append("\n## Current Content Preview\n")
        preview = current_content[:500].strip()
        report_lines.append(f"{preview}...\n")

src/devlens/server.py:162-175 (registration)

The MCP tool registration and wrapper function tool_monitor_changes that delegates to the monitor_changes helper.

@mcp.tool()
async def tool_monitor_changes(url: str, previous_hash: str | None = None) -> str:
    """Check if a page has changed.

    Tracks content modifications over time.

    Args:
        url: URL to monitor.
        previous_hash: Previous content hash to compare against.

    Returns:
        Change detection report with content hash.
    """
    return await monitor_changes(url, previous_hash)

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