Files · Google Gemini MCP Server for SMB Business Intelligence

# Google Gemini MCP Server for SMB Business Intelligence
 
> A turnkey MCP server that lets SMB teams use natural language to query their business data from HubSpot, Stripe, and Google Calendar via a secure Gemini-powered interface.
 
## Architecture
 
This solution bundles a multi-tenant MCP server that exposes business tools as MCP endpoints. It provides tenant isolation via `@reaatech/mcp-gateway-core`, budget enforcement via inline primitives, and LLM observability via Langfuse. A Next.js chat UI connects to Google Gemini (via `@ai-sdk/google`), which calls MCP tools to fetch and aggregate data from HubSpot, Stripe, and Google Calendar.
 
### Exposed MCP Tools
 
**HubSpot**
- `hubspot_search_contacts` — Search contacts by query string
- `hubspot_search_deals` — Search deals by name or amount range
- `hubspot_list_recent_deals` — List recent deals sorted by close date
 
**Stripe**
- `stripe_list_customers` — List customers with optional email filter
- `stripe_list_invoices` — List invoices with optional status/customer filter
- `stripe_list_subscriptions` — List subscriptions with optional status/customer filter
 
**Google Calendar**
- `google_calendar_list_events` — List upcoming events for a calendar
- `google_calendar_list_calendars` — List accessible calendars
 
## Setup
 
1. **Clone and install**
   ```bash
   pnpm install
   ```
 
2. **Configure environment**
   Copy `.env.example` to `.env` and fill in your credentials:
   ```bash
   cp .env.example .env
   ```
   Required vars: `SUPABASE_URL`, `SUPABASE_SECRET_KEY`
   Optional: `HUBSPOT_ACCESS_TOKEN`, `STRIPE_SECRET_KEY`, `GEMINI_API_KEY`, etc.
 
3. **Run**
   ```bash
    pnpm dev              # next dev — http://localhost:3000
    pnpm build            # next build
    pnpm test             # vitest run with coverage
    pnpm typecheck        # tsc --noEmit
    pnpm lint             # eslint .
   ```
 
## Tenant Configuration
 
Place YAML config files under `./tenants/` (configurable via `TENANT_CONFIG_PATH`). Loaded by `loadTenantsAsync()` from `@reaatech/mcp-gateway-core`:
 
```yaml
tenantId: acme-corp
displayName: Acme Corp
auth:
  apiKeys:
    - keyHash: <sha256>
      name: admin-key
rateLimits:
  requestsPerMinute: 100
  requestsPerDay: 10000
cache:
  enabled: true
  ttlSeconds: 300
allowlist:
  mode: allow
  tools:
    - hubspot_*
    - stripe_*
upstreams:
  - name: main
    url: https://mcp.internal.corp
```
 
## Prior Failure Fix
 
All cost calculations include null-safety guards on token counts before calling `.toFixed()`. The `GeminiPricingProvider.validateEstimateArgs()` method checks for null, undefined, NaN, and negative values before any arithmetic operations, preventing `TypeError: Cannot read properties of null (reading 'toFixed')`.
 
## Project Layout
 
```
app/                  Next.js App Router pages + API routes
src/
  lib/                Shared types, env config, tool definitions, handlers
  lib/tool-handlers/  Business logic for HubSpot, Stripe, Google Calendar
  instrumentation.ts  Next.js instrumentation hook (Langfuse init)
tests/                Vitest suite (mirrors src/)
packages/             API references for every dependency
```
 
## License
 
MIT — see [LICENSE](./LICENSE).