Getting Started

Tariff (@atriumn/tariff) is an MCP server that provides real-time LLM pricing data. It runs as a local process and communicates over stdio.

Prerequisites

• Node.js 18+ — download

That’s it. No API keys, no accounts, no configuration files.

Install in Claude Code

The fastest way to get started:

claude mcp add tariff -- npx -y @atriumn/tariff

This registers the MCP server and it will be available in all future Claude Code sessions.

Install in Cursor

Add to your Cursor MCP config (.cursor/mcp.json):

{
  "mcpServers": {
    "tariff": {
      "command": "npx",
      "args": ["-y", "@atriumn/tariff"]
    }
  }
}

Manual MCP config

For other MCP clients, the server config is:

{
  "mcpServers": {
    "tariff": {
      "command": "npx",
      "args": ["-y", "@atriumn/tariff"]
    }
  }
}

Your first query

Once installed, just ask your AI assistant a pricing question in natural language:

“How much does Claude Sonnet 4.5 cost per million tokens?”

The assistant will call the get_model_details tool and return something like:

Model: claude-sonnet-4-5
Provider: anthropic
Mode: chat

Pricing (per 1M tokens):
  Input:  $3.00
  Output: $15.00

Context Window:
  Max Input:  200K
  Max Output: 8K

Capabilities: vision, function_calling, parallel_function_calling

How it works

1. On first use, the server fetches pricing data from the LiteLLM community registry
2. Data is cached in-memory for 24 hours (with a disk fallback)
3. Your AI assistant calls one of the 4 tools via the MCP protocol
4. Results are returned as formatted text

No data leaves your machine — the only network request is fetching the public pricing registry.