Use FastMCP tags + visibility control for profile-based tool loading

[dtehan-td]

Summary

Replace the current regex-based profile module loading with FastMCP v3 tags + mcp.disable(tags=...) so all tools are registered at startup and profile filtering happens via tag-based enable/disable with automatic list_tools updates.

Background

Currently, profiles determine which tools are registered via regex pattern matching on tool name prefixes in module_loader.py. Disabling a tool post-startup is not supported. FastMCP v3 allows attaching tags at registration time and calling mcp.disable(tags=...) to hide tools from clients dynamically — disabled tools are excluded from list_tools and trigger notifications/tools/list_changed automatically.

Proposed Approach

TAG_MAP = {"base_": "base", "dba_": "dba", "rag_": "rag", ...}

def tag_for(tool_name: str) -> set[str]:
    for prefix, tag in TAG_MAP.items():
        if tool_name.startswith(prefix):
            return {tag}
    return set()

# Register all tools with tags
mcp.tool(name=name, tags=tag_for(name))(wrapped)

# Apply profile: disable tools not in the allowed set
allowed_tags = profile_allowed_tags(profile_name)
mcp.disable(tags=all_tags - allowed_tags)

Files to Change

• app.py:80-116 (feature flags)
• app.py:530-583 (registration loop)
• module_loader.py (can be simplified)
• tools/__init__.py

Value

• Dynamic enable/disable at runtime without re-registration.
• list_tools automatically excludes disabled tools — progressive disclosure is simplified.
• notifications/tools/list_changed sent automatically when tools are enabled/disabled.
• Simplifies module_loader.py — regex matching replaced by tag lookup.

Dependencies

Should be done together with Lifespan management (#9). The profile filter needs the lifespan-supplied connection to discover analytic functions.