model-cost-mcp

A small MCP server that lets an AI agent answer "which model should I use, and what will it cost?" for image, video, audio and 3D generation, with prices that are exact and errors the agent can recover from.

The catalog is sample data: the models and prices are invented for the demo. It is not affiliated with any provider. Replace src/catalog.ts with a real catalog before relying on the numbers.

Tools

Related MCP server: CloudCost MCP Server

Design choices

• Money is integers. Prices are stored in millionths of a dollar, so there is no floating-point drift. The billed amount rounds the exact cost up to the next whole cent, so any surface that computes from the same inputs shows the same number.

• Per-second models bill every started second, and the response says when it rounded.

• Errors tell the agent what to do next. An invalid call returns a code, a message, a hint with an example call, and for unknown model ids the closest valid ids. Nothing throws an opaque exception.

• Tool descriptions are written for model selection. Each says when to call it and what it needs, and every catalog entry carries a use_when line.

Run

npm install
npm test          # 9 tests, in-memory MCP client against the real server
npm run typecheck
npm start         # stdio server

Add it to an MCP client such as Claude Desktop:

{
  "mcpServers": {
    "model-cost": {
      "command": "npx",
      "args": ["tsx", "/absolute/path/to/model-cost-mcp/src/index.ts"]
    }
  }
}

Example

estimate_cost { "model_id": "demo/video-draft", "quantity": 3, "seconds": 4.2 }
-> 3 clips x 5s = 15 billable seconds, exact $0.750000, billed $0.75
   note: "Every started second is billed, so 4.2s is billed as 5s."

estimate_cost { "model_id": "demo/video-cinema", "quantity": 2 }
-> error seconds_required
   hint: Call again with seconds, for example {"model_id": "demo/video-cinema", "quantity": 2, "seconds": 5}.

Not done yet

• The catalog is a hard-coded list, not a live source.

• stdio only; no HTTP transport or authentication.

• No currency conversion, taxes or volume discounts.