Architectural strategy now requires a shift from “Integration-First” (REST) to “Intelligence-First” (MCP/A2A). While REST remains essential — MCP and A2A are layered on top of it. Agentic protocols determine how that plumbing is used by autonomous entities.
This article outlines the comparison and implementation patterns in Pega.
1. The Architectural Comparison: Choosing Your Protocol
In a Pega environment, we distinguish these by “Static Integrations” to “Dynamic Tooling” and “Collaborative Agents.”
| Feature | REST API (Traditional) | MCP (Model Context Protocol) | A2A (Agent-to-Agent) |
|---|---|---|---|
| Logic Owner | The Developer (Hard-coded) | The LLM (Autonomous discovery) | The LLM (Agentic Orchestration) |
| Use Case | Data exchange between systems. | Ability to run external tools autonomously | Delegate tasks between autonomous agents across systems. |
| Pega Artifact | Connect-REST / Service-REST | Tool Rules & Data Pages | Agent & Tool Rules |
| Analogy | A rigid contract/manual. | The agent’s toolbox. | The agent’s intercom system. |
2. Implementation in Pega Infinity
REST API: The Foundation
REST is the baseline. You still need it for standard system-to-system synchronisation where reasoning isn’t required.
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Implementation: Standard Connect REST rules.
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Tip: Use DX API v2 for all REST calls to ensure the data structures are “Agent-Ready” (JSON-native).
MCP: The “Dynamic Tool” Layer
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Pega can act as a MCP server or a MCP client.
- Being a MCP server, it can expose the workflows and data to external agents
- Being a MCP client, Pega enables its agents to invoke tools and data from external MCP bridges autonomously.
A2A: The “Collaboration” Layer
It’s for when a “Functional Agent” in App A needs a “Specialist Agent” in App B to finish a task. Or say an Agent in a Pega App A needs to connect to a specific external Agent autonomously.
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Agent Cards: Every Pega agent publishes an
/.well-known/agent.json(Agent Card). -
Versioning : Like APIs, Agents can be versioned enabling support for multiple clients and easier rollouts.