157 MCP Tools: How We Built the Largest Agent-Callable Surface in Martech
When we launched SpiderIQ, we had 12 tools. Today, we ship 157 MCP tools across 5 dedicated servers — the largest agent-callable surface in martech. Here's how we got here, and why MCP is the right bet.
Why Model Context Protocol?
Most automation platforms expose REST APIs. Agents can call them, sure — but every integration requires bespoke glue code: auth wrappers, pagination handling, error mapping. MCP eliminates this entirely by providing a standardized tool-calling interface that any LLM agent understands natively.
We evaluated GraphQL federation, gRPC, and OpenAPI-based approaches. MCP won because it optimizes for the agent's mental model, not the developer's. A tool is a function with typed parameters and a structured response — nothing more.
The Five-Server Architecture
Our 157 tools are distributed across five MCP servers, each owning a bounded domain:
• SpiderMaps (42 tools) — Location intelligence, POI scraping, geo-enrichment
• SpiderVerify (31 tools) — Email/phone validation, deliverability scoring
• SpiderMail (28 tools) — Campaign orchestration, template management, sending
• SpiderCRM (34 tools) — Contact management, deal pipeline, activity tracking
• SpiderAdmin (22 tools) — Billing, usage analytics, team management
Multi-Tenant Isolation
Every MCP call passes through our isolation layer. The agent's session token is scoped to a specific tenant, and tool execution happens inside a sandboxed worker pool. No tenant can ever read another tenant's data — even if the agent hallucinates a cross-tenant ID.
Schema Validation
Each tool's input schema is validated at the gateway level before execution begins. We use JSON Schema draft-2020 with strict mode enabled, rejecting any undeclared properties. This catches malformed agent calls before they hit business logic.
What's Next
We're working on tool composition — letting agents chain multiple tools into atomic transactions. Think: "scrape 50 restaurants, verify all emails, create a campaign, and schedule it" as a single, rollback-safe operation.
If you're building agent infrastructure, we'd love to compare notes. Reach out at engineering@spideriq.ai.