This article is the second in a two-part series. The first article can be found here: Where are you placing your CX chips? Generalist Super Agent or Multiple Specialized Agents?
The smartest play is neither an all-knowing Super-Agent nor a swarm of siloed specialist agents—it’s a hybrid: a powerful generalist agent (with several agent personas) that steers the conversation, flanked by specialist agents that fire off API/tool calls, search the web, tap knowledge bases, and trigger tools on demand.
This only works if agents can talk to each other, to your data and tools, and to humans using open, reusable protocols—so you wire a connector once and reuse it everywhere instead of rebuilding brittle point-to-points.
This guide shows revenue and CX leaders how to sidestep agent-sprawl and integration chaos—and why Cast’s open-protocol fabric puts you two steps ahead of vendor lock-in.
Your agents must interoperate with:
Open protocols give agents a shared language. Wire it once, reuse it everywhere—no more brittle one-off connectors.
Agents need to talk to data, each other, and humans.
Agent ↔︎ Data: MCP, MCP Proxy Bridge
Agent ↔︎ Agent: ACP, A2A
Agent ↔︎ Human: A2H, H2A
Below are five key protocols that form an end-to-end fabric for data access, inter-agent hand-offs, and human collaboration.
MCP lets agents discover tools and call them to query or act on external systems (files, DBs, SaaS APIs, code execution). It’s bidirectional under policy—not read-only.
Think of MPB as a thin wrapper that lets REST/webhook apps—HubSpot, Zendesk, you name it— present an MCP-compatible façade and an optional A2A handoff shim until a native agent exists.
It solves legacy lock-in—use it when you must integrate a non-compliant system today and don’t want to rebuild tomorrow.
Why execs care
Example: A legacy CRM exposes a renewal endpoint; MPB masks its quirks so every agent treats it like a modern MCP source.
ACP is an open agent↔agent standard to reduce fragmentation and enable collaboration across stacks;
IBM contributed BeeAI—powered by the open Agent Communication Protocol (ACP)—to the Linux Foundation, establishing open, community governance for ACP and its reference implementation.
Important naming note on “ACP.” There are two unrelated ACPs in the market:
A2A defines how agents discover capabilities, delegate tasks, exchange artifacts, and manage lifecycles across frameworks and vendors; transport-agnostic, usable within or across org boundaries.
A2A introduces Agent Cards for capability discovery and standardizes task lifecycle and artifact exchange, with transport over HTTP/SSE/JSON-RPC.
A smart escalation layer: agents decide when to loop in a human, picking the right person, channel, and context.
It solves moments where empathy or judgment boosts revenue or mitigates risk—use A2H when a human touch can save, upsell, or de-risk.
Example: Usage spikes trigger an A2H alert to the VP via email (complete with benchmarks); after approval, the agent resumes automated upsell steps.
The mirror image of A2H—a secure command interface so people can instruct agents to act on their behalf.
It solves high-trust tasks that are faster or safer for an agent to execute. Invoke H2A whenever a human needs precise, error-free action.
Example: A finance manager tells the Payments Agent to issue a refund via Stripe, or a support rep asks the Security Agent to trigger 2-factor authentication for a user.
With these six protocols in place, your hybrid agent ecosystem—generalist strategists plus deep specialists—can share data, delegate work, and involve humans only when it truly counts.
BTW, if you are running cast.app agents, all the complexity solved for you.
Rule of thumb: A2A handles “what/why/results,” ACP standardizes “who/where/allowed,” MCP is “how to access systems.”
Cast.app weaves six pieces of connective tissue—MCP, MCP Proxy Bridge, ACP, A2A, A2H, and H2A—into one seamless fabric so your AI CSMs, Feedback Agents, and Support Agents operate like a single, revenue-focused brain.
What this means for leaders
Scale revenue, not teams—Cast.app handles the wiring.