Every agent in your org needs two things: a way to reach outside tools (a calendar, a database, a search API) and a way to talk to agents outside your own build. Hand-wiring both, per agent, per integration, is how orgs rot — one bespoke function call at a time.
MCP (Model Context Protocol) standardizes the first: a common interface an agent uses to reach a tool or data source, so any MCP-speaking agent can use any MCP-exposed tool with no custom glue code. A2A (Agent2Agent) standardizes the second: a common way for one agent to hand off work to another agent it doesn't control — including one built on an entirely different framework. Reach for MCP when your agent needs a tool it doesn't have built in; reach for A2A when you need a specialist agent outside your own system.
Run the seed: decide which protocol a real handoff needs, and justify it by naming what's actually being crossed — a tool boundary or an agent boundary.