Spillmark MCP Server

by spillmark Your server? Claim it

answering

Spillmark is answering right now. Last checked 4 min ago. It exposes 3 tools.

Free Amazon and Meta ads calculators. No brand data and no key.

Uptime history 9 days of history · worst day 5%

9 days agonow

89.0%

Uptime 24h

81 of 91 checks

Tools

read from the server

249 ms

Response time

average over 24h

open, no key

Access

streamable-http

What changed 1

Every tool that appeared, vanished or quietly changed what it asks for. Recorded since 29 October 2026. No other catalogue keeps this.

29 Oct a tool description was rewritten list_calculators

Spillmark does not always answer

Over the last week it answered 29.3% of our checks. We check every 15 minutes, so you hear about the next outage within the hour — not from your users.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 4 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

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

Settings → Connectors → Add custom connector, then paste this address

https://spillmark.com/mcp

~/.codex/config.toml

[mcp_servers.spillmark]
url = "https://spillmark.com/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "spillmark": {
      "url": "https://spillmark.com/mcp"
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "spillmark": {
      "type": "http",
      "url": "https://spillmark.com/mcp"
    }
  }
}

Available tools 3

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

calculator

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 means 15%), choices as the option index.

calculators

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_calculator to run one.

how

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.

Endpoints

URL	Transport	State	Latency	Checked
https://spillmark.com/mcp	streamable-http	answering	205 ms	4 min ago

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Spillmark — questions

Answers built from our own checks of this server.

What can Spillmark do?

It exposes 3 tools, read directly from the server on our last check. Among them: how_lift_is_calculated, list_calculators, run_calculator. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is Spillmark working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 81 of 91 checks got a reply (89.0%), average response time 249 ms. The bar chart above shows every period we have measured.

How do I connect Spillmark?

Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does Spillmark need an API key?

No. Spillmark completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 3 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is Spillmark?

It answers our handshake in 249 ms on average, which is faster than 56% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.