Testing Back in Stock Subject Lines in Continue
Restock notifications convert when they reach inboxes fast and feel urgent. With Continue connected to marginal's email MCP server, you can generate, launch, and evaluate back in stock subject lines without leaving your coding environment.
Why pair Continue with back in stock campaigns
Back in stock emails are time-sensitive — a customer who waited for an item wants to know the moment it returns, and the subject line decides whether they open before someone else buys it out. Testing those lines methodically beats guessing.
Continue is an open-source AI coding assistant that supports MCP, so it can call marginal's tools directly. That means a developer or growth engineer can drive a full subject line A/B test through natural prompts while still working in their normal flow.
- Generate restock-themed subject variants on demand
- Launch a managed send without juggling separate dashboards
- Pull open and click metrics back into your editor session
- Keep iteration close to where you already build campaigns
Tools you'll use for a subject line test
marginal exposes four MCP tools. For a back in stock subject line test you typically chain them in order, letting the AI agent handle email marketing tasks while you review each step.
- generate_variants — produce candidate restock subject lines, from urgency-driven to scarcity-driven angles
- launch_test — start the subject line A/B test and trigger the managed send
- get_results — track opens, clicks, and within-test lift as the test runs
- recommend_next — get a data-backed suggestion for the next iteration or winner
A practical back in stock workflow in Continue
Start by asking Continue to generate variants for your restock audience — for example, framing the same item with different hooks like 'It's back', 'Your size is in stock again', or a countdown angle. Review the output, then have Continue launch the test.
Once the send is out, ask for results periodically. marginal reports open and click tracking plus within-test lift so you can see which back in stock subject line is pulling ahead, then promote the winner or run a follow-up round.
- "Generate 4 back in stock subject lines for a sneaker restock"
- "Launch an A/B test with these variants"
- "Show me current open and click results"
- "Recommend the next subject line to try"
Getting connected
marginal is hosted, so there's nothing to self-host. Point Continue's MCP configuration at https://marginal.sh/mcp and authenticate with your Bearer API key (marg_live_...). The free tier covers 100 experiments per month, which is plenty for getting a restock subject line program off the ground.
See the MCP endpoint at https://marginal.sh/mcp and the docs at https://marginal.sh/docs/ for setup details and tool references.
Get started with marginal
marginal is a hosted email marketing MCP server at marginal.sh. Sign up free, create an API key, and connect https://marginal.sh/mcp from Cursor, Codex, or Claude Desktop.
- 100 experiments/month on the free tier
- Four MCP tools: generate_variants, launch_test, get_results, recommend_next
- Listed in the MCP Registry as sh.marginal/mcp