MCP, A2A, and the End of Vendor Agent SDKs
Model Context Protocol and Agent-to-Agent are quietly doing to agent tooling what HTTP did to proprietary networking stacks — and it changes what you should build in-house.
For most of 2024 and 2025, connecting an agent to a tool meant writing a bespoke integration against whichever framework you'd standardized on — LangChain tools, a custom function-calling schema, or a vendor's proprietary plugin format. Every new data source or internal system meant another adapter, tied to that one framework, thrown away the moment you switched.
Two protocols are changing that, and it's worth being precise about what each one actually does, because they get conflated constantly.
Model Context Protocol (MCP) standardizes how an agent talks to a tool or data source. An MCP server exposes resources, tools, and prompts through a fixed schema; any MCP-compatible client — regardless of which model or framework it's running — can discover and call them the same way. The practical effect: a team building an internal MCP server for, say, their ticketing system writes that integration once, and it works against any agent runtime that speaks MCP, not just the one they happened to build it for first.
Agent-to-Agent (A2A) solves a different problem: how one agent discovers and delegates to another agent, potentially built by a different team, on a different stack, without either side needing to know the other's internals. Where MCP is about an agent reaching down into tools and data, A2A is about agents reaching sideways into other agents — think a procurement agent that can hand off a sub-task to a legal-review agent it doesn't own and doesn't need to trust beyond a defined interface.
Why this matters more than it sounds like
The HTTP comparison isn't a stretch. Before a common transport protocol existed, every application that wanted to talk to another had to negotiate its own wire format — and every one of those pairings was a maintenance liability that scaled with the number of systems, not linearly but combinatorially. Standardized interfaces don't just save integration work; they change what's rational to build at all. Nobody writes a custom TCP stack per application anymore, and in a few years, we expect "custom tool-calling schema per agent framework" to look similarly anachronistic.
The concrete implication for anyone building agent systems now: the tool integration layer is becoming infrastructure, not application logic. If you're currently maintaining framework-specific adapters for your internal systems, that maintenance burden is a temporary tax, not a permanent feature of the landscape — and it's worth building your next integration against MCP directly rather than against whatever agent framework happens to be popular this quarter, because the framework is far more likely to change than the protocol underneath it.
The honest caveat: both protocols are young, the tooling ecosystems around them are uneven, and "standard" today still means "the standard with the most momentum," not "the only game in town." Treat this as a strong signal about direction, not a finished migration checklist.