Conditional Activation (Fallback Skills)
Skills can automatically show or hide themselves based on which tools are available in the current session. This is most useful for fallback skills - free or local alternatives that should only appear when a premium tool is unavailable. Field Behavior fallback_for_toolsets Skill is hidden when the listed toolsets are available. Shown when they're missing. fallback_for_tools Same, but checks individual tools instead of toolsets. requires_toolsets Skill is hidden when the listed toolsets are unavailable. Shown when they're present. requires_tools Same, but checks individual tools. Example: The built-in duckduckgo-search skill uses fallback_for_toolsets: [web] . When you have FIRECRAWL_API_KEY set, the web toolset is available and the agent uses web_search - the DuckDuckGo skill stays hidden. If the API key is missing, the web toolset is unavailable and the DuckDuckGo skill automatically appears as a fallback. Skills without any conditional fields behave exactly as before - they're always shown.
From the official Hermes Agent documentation.
metadata:
hermes:
fallback_for_toolsets: [web] # Show ONLY when these toolsets are unavailable
requires_toolsets: [terminal] # Show ONLY when these toolsets are available
fallback_for_tools: [web_search] # Show ONLY when these specific tools are unavailable
requires_tools: [terminal] # Show ONLY when these specific tools are available