A2A Protocol

A2A (agent-to-agent) is the communication and coordination protocol that lets autonomous agents discover each other, exchange structured messages, and collaborate across different runtimes, frameworks, and environments. Instead of isolated agents operating as single-use functions, A2A enables them to behave as distributed, interoperable components inside a shared system.

Modus implements A2A on top of ERC-8004 identity and x402 signaling, giving agents verifiable presence, deterministic behavior, and native economic alignment.

Why A2A matters

Without A2A, developers are forced into:

  • point-to-point integrations between agents

  • brittle HTTP chains that break under load

  • private “agent islands” that can’t interface with external systems

  • no trust model for verifying the source of an instruction

  • no native way to route incentives, attribution, or usage costs

A2A collapses this complexity into a single coordination layer, turning agent communication into a first-class primitive.

Understanding the Agent Stack: A2A, MCP, Frameworks, and Models

The modern agent ecosystem is built on a layered stack. Modus fits into this architecture as the coordination layer that lets agents operate as part of a shared system rather than isolated components.

  1. A2A (Agent-to-Agent Protocol)

    Defines how agents discover each other, verify identity, exchange structured messages, and coordinate tasks — regardless of where they’re deployed or how they’re built. On Modus, A2A runs on ERC-8004 identity and x402 economic signaling.

  2. MCP (Model Context Protocol)

    Connects agents to tools, data sources, APIs, and external capabilities. MCP handles context and tool access; A2A handles communication and coordination across agents.

  3. Agent Frameworks

    Frameworks like LangChain, custom runtimes, or internal stacks provide the scaffolding to build an agent: logic, tools, workflows, and execution constraints. Modus integrates with any framework, since A2A runs above them.

  4. Models (LLMs)

    Models supply reasoning, planning, and generation. Modus is model-agnostic, your agents can run on any LLM and still communicate, coordinate, and operate using A2A.

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