Spillmark

Connect Remote server

claude mcp add --transport http spillmark https://spillmark.com/mcp --header "Authorization: Bearer <YOUR_API_KEY>"

{
  "mcpServers": {
    "spillmark": {
      "url": "https://spillmark.com/mcp",
      "headers": {
        "Authorization": "Bearer <YOUR_API_KEY>"
      }
    }
  }
}

{
  "servers": {
    "spillmark": {
      "type": "http",
      "url": "https://spillmark.com/mcp",
      "headers": {
        "Authorization": "Bearer <YOUR_API_KEY>"
      }
    }
  }
}

Settings > Connectors > Add custom connector
URL: https://spillmark.com/mcp

Replace the values in angle brackets with your own. Keys stay on your machine; we never see them.

Tools 3 found in our last check

• list_calculators

  Spillmark's free Amazon and Meta ads calculators (holdout test size, brand-size MDE, geo holdout states, ad waste, Meta ROAS reality check, incremental ROAS, break-even ROAS, ACoS, TACoS, Amazon fees and profit, LTV and CAC), with each one's inputs and example values. Use run_ca…

• run_calculator

  Runs one calculator from list_calculators on your numbers and returns the headline result, the supporting figures, a one-sentence reading, and a link that opens the calculator with the same inputs. Missing inputs use the calculator's example values. Enter percents as points (15…

• how_lift_is_calculated

  Spillmark's method in brief: how a geo holdout test measures the sales Meta ads cause on Amazon, with links to the full method and a sample report on made-up numbers.

Headers

Details

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