CostGate

Gate your MCP. Cut your bill.

CostGate reduces AI token consumption by optimizing MCP tool definitions and responses. Cursor-first, compatible with Claude Desktop and other MCP clients.

Repository layout (monorepo)

costgate/
├── packages/
│   ├── schema/     @costgate/schema   — shared log schema
│   ├── probe/      @costgate/probe    — measurement MCP (npm)
│   └── gate/       costgate-gate      — gateway MCP (Go binary)
├── docs/
├── examples/
└── scripts/

See docs/structure.md for why Probe and Gate share one repo.

Related MCP server: PlanckBot

Packages

Quick start (Probe)

npm install
npm run build:probe

Add to Cursor ~/.cursor/mcp.json:

{
  "mcpServers": {
    "costgate-probe": {
      "command": "node",
      "args": ["/path/to/costgate/packages/probe/dist/index.js"],
      "env": {
        "COSTGATE_PROBE_LOG_DIR": "~/.costgate/logs"
      }
    }
  }
}

Or after npm publish: npx @costgate/probe

See examples/cursor/ for full configuration.

Quick start (Gate)

Requires Go 1.25+.

npm run build:gate
npm run test:gate   # smoke test (GitHub backend via ~/.costgate/backends.json)

Add to Cursor ~/.cursor/mcp.json (keep serena direct; see mcp-gate-github.json):

{
  "mcpServers": {
    "costgate-gate": {
      "command": "/path/to/costgate/packages/gate/bin/costgate-gate",
      "env": {
        "COSTGATE_CONFIG": "~/.costgate/backends.json"
      }
    }
  }
}

Filter mode (default): Tier A/B/C + discover_tools / invoke_tool. Set COSTGATE_GATE_MODE=transparent for pass-through baseline. See packages/gate/README.md.

Compare reduction: npm run compare (Before/After tools/list token estimate).

Production Cursor setup: npm run cursor:production — see examples/cursor/README.md.

Plans (roadmap)

Documentation

• Development roadmap

• Repository structure

• Docker / Dev Container

• Architecture

• Log schema

• Contributing

License

MIT — see LICENSE