@ongravy/mcp-server

Production MCP (Model Context Protocol) server exposing OnGravy's accounting / tax / audit toolkit (60+ tools) to any MCP-compatible client — Claude Desktop, Cursor, Zed, custom apps.

What this gives you

Once installed in your Claude Desktop config, you can ask the model questions like:

• "Show me top 10 customers by revenue this quarter"
• "What's my GST liability for May 2026?"
• "Which invoices are overdue beyond 60 days?"
• "Look up the e-invoice rule for high-value B2B transactions"

…and Claude reaches into a live OnGravy backend, runs the appropriate tool with proper authorisation, and answers from real data.

Installation

npm install -g @ongravy/mcp-server

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):

{
  "mcpServers": {
    "ongravy": {
      "command": "ongravy-mcp",
      "env": {
        "ONGRAVY_API_TOKEN":   "<personal access token>",
        "ONGRAVY_BUSINESS_ID": "<business uuid>",
        "ONGRAVY_BASE_URL":    "https://app.ongravy.com"
      }
    }
  }
}

Restart Claude Desktop. The OnGravy tools appear in the tool picker.

Architecture

Claude Desktop / Cursor / Zed → MCP wire (JSON-RPC over stdio)
       │
       ▼
@ongravy/mcp-server (this package)
       │
       │  ↓ HTTPS w/ bearer token ↓
       │
  OnGravy backend
  (60+ tools across 4 jurisdictions)

The MCP server is intentionally thin: it's a stdio adapter that translates between MCP wire format and OnGravy's HTTP API. All business logic lives in the main app; this package only forwards calls. Stateless — no DB, no secrets stored.

Sample tools (8 reference implementations)

The package ships with 8 pure-compute reference tools that demonstrate the pattern:

| Tool | Purpose | |---|---| | compute_gst | CGST + SGST + IGST split on a sale (intra/inter-state aware) | | format_invoice_number | INV/2026-27/0042-style invoice numbering | | check_msme_due_date | Sec 16 MSMED Act 45-day deadline checker | | validate_gstin | 15-character GSTIN format + checksum validation | | classify_tds_section | Heuristic 194C/I/J/H/Q TDS-section classifier | | validate_pan | PAN format + entity-type decoder | | compute_msme_interest | Compound interest at 3× RBI bank rate (Sec 16) | | check_269st_violation | Sec 269ST cash-receipt limit + 100% penalty alert |

Auth model

Each user obtains a personal-access token from app.ongravy.com → Settings → MCP. The MCP server passes it as Authorization: Bearer <token> on every backend call. The backend resolves it to a user, applies row-level security, and gates tools by permission level.

Why this is interesting

• First production MCP server for accounting — most MCP servers in the wild are demos (file-system, sqlite, github). This one drives a real-money domain with auth, audit trails, and jurisdiction gating.
• 60+ tools, four jurisdictions (India, UAE, Saudi Arabia, Singapore) — broad surface area MCP clients have not seen before.
• Six-layer hallucination defence in the upstream OnGravy backend (retrieval grounding → schema-constrained output → referential probes → idempotent writes → audit log → cost cap). End-to-end hallucination rate measured at ~0.3%.
• Pure-tested format conversion — 38 tests covering MCP-name sanitisation, non-object schemas, jurisdiction filtering, and per-tool correctness.

Read the full writeup: Six-layer hallucination defence.

Local development

git clone https://github.com/pratikrevankar/ongravy
cd ongravy/mcp-server
npm install
npm test            # 38 tests
npm run build       # TypeScript → dist/

To smoke-test against your local Claude Desktop, point the config at dist/index.js directly:

{
  "mcpServers": {
    "ongravy": {
      "command": "node",
      "args": ["/absolute/path/to/ongravy/mcp-server/dist/index.js"],
      "env": { "ONGRAVY_API_TOKEN": "...", "ONGRAVY_BUSINESS_ID": "..." }
    }
  }
}

Author

Pratik Revankar — building OnGravy, an AI-native accounting platform for India launching June 2026.

@pratikrevankar on X.

License

MIT — fork freely.