Spillmark

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

• Connection: Runs in the cloud
• Transport: Streamable HTTP
• Category: Online shops & payments
• You need to fill in: Authorization

Install

Pick the AI app you use, then copy the settings.

You need

• Runs in the cloudNothing to install; it connects over the internet

Which app do you use?

claude mcp add --transport http spillmark https://spillmark.com/mcp --header 'Authorization: your-value'

{
  "mcpServers": {
    "spillmark": {
      "url": "https://spillmark.com/mcp",
      "headers": {
        "Authorization": "your-value"
      }
    }
  }
}

{
  "servers": {
    "spillmark": {
      "type": "http",
      "url": "https://spillmark.com/mcp",
      "headers": {
        "Authorization": "your-value"
      }
    }
  }
}

Your choice stays on this device in a cookie; no account needed.

Values you fill in

• Authorization secret HTTP header
  Optional. 'Bearer sm_...' from Settings -> Agent access, for a brand's own profit and incrementality record. Public tools need no key.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Tool names and descriptions exactly as the server reported them on Nov 8, 2026. The maker wrote them, not us; we show them as plain text.

• 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_cal

• 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 m

• 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.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 8, 2026

• ✓ Pass

  Maker matches the repo

  The registry name was verified against the domain spillmark.com (the registry checks domain ownership)

• … Not checked yet

  Still maintained

  We have not read this repo from GitHub yet

• … Not checked yet

  Has a licence

  We have not read this repo from GitHub yet

• ✓ Pass

  Endpoint responds

  Responded in 412 ms (HTTP 200)

• – Not applicable

  Sign-in with OAuth

  No sign-in needed

• ✓ Pass

  No hidden instructions in tool descriptions

  Read 3 tool descriptions and found no hidden instructions to the AI

Compared with others in Online shops & paymentsi

• More stars than 0% of the other 2554 servers in this category
• Published to the registry more recently than 91% of the other 2554 servers in this category
• Basic checks equal to or better than 100% of the other 2554 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

README from the maker

{

claude mcp add --transport http spillmark https://spillmark.com/mcp