subject-line-lablisted

# Subject Line Lab Stop A/B testing blind. This skill reads **your actual last 100+ sends**, finds the subject-line patterns that correlate with open rate on *your* list, and generates 20 tuned candidates for your next campaign. **Requires:** Cogny MCP + a connected ESP (Klaviyo, Mailchimp, Rule, or Get a Newsletter). [Sign up](https://cogny.com) ## Usage `/subject-line-lab` — mine patterns and generate generic candidates `/subject-line-lab "Black Friday doors open"` — mine patterns and generate candidates for a specific campaign topic ## Prerequisites Check Detect which ESP is connected. Check **both** namespaces (Cloud-aggregated via `mcp__cogny__<svc>__*` and Solo/Lite per-ESP via `mcp__<svc>__*`): - Klaviyo → `mcp__cogny__klaviyo__*` or `mcp__klaviyo__*` - Mailchimp → `mcp__cogny__mailchimp__*` or `mcp__mailchimp__*` - Rule → `mcp__cogny__rule__*` or `mcp__rule__*` - Get a Newsletter → `mcp__cogny__get_a_newsletter__*` or `mcp__get_a_newsletter__*` If none are connected: ``` This skill requires a connected ESP via Cogny MCP. Connect Klaviyo, Mailchimp, Rule, or Get a Newsletter at https://cogny.com ``` If multiple are connected, prompt the user which one to analyze (or analyze all, labeled). ## ESP tool adapter Each ESP exposes subject-line history differently. Use the right tool per connected service: | ESP | Send history tool | Notes | |-----|-------------------|-------| | Klaviyo | `list_campaigns` (channel=email) then `get_campaign` | Tools are bare-named