Two protocols, two layers
A2A (Agent-to-Agent Protocol) and I-Lang address different parts of the multi-agent stack. A2A handles how agents find and talk to each other. I-Lang handles how agents understand what to do.
| Dimension | A2A | I-Lang |
|---|---|---|
| Created by | Google (now Linux Foundation) | I-Lang Research (open community) |
| Primary function | Agent discovery, capability negotiation, task delegation | Instruction structure, behavioral definitions, communication format |
| Layer | Agent coordination layer | Semantic instruction layer |
| Requires | Agent Card server, JSON-RPC endpoint | Nothing. Text-native, works in any conversation |
| Format | JSON-RPC, Agent Cards, Task objects | Structured text: [VERB:@TARGET|mod=val] and ::GENE{} |
| Solves | How Agent A finds and delegates work to Agent B | How any agent understands its instructions and behavioral constraints |
When to use A2A
Use A2A when you have multiple agents that need to discover each other, negotiate capabilities, and delegate tasks. A2A is the coordination layer: it handles the handshake between agents, not what happens after the handshake.
When to use I-Lang
Use I-Lang when you need an agent to follow instructions precisely, maintain behavioral consistency, and communicate in a structured format. I-Lang works at the instruction layer: it defines what an agent does and how it behaves, regardless of how that agent was discovered or delegated to.
Using them together
A2A connects agents. I-Lang structures what those agents say to each other.
Example: Agent A uses A2A to discover Agent B (a data analyst). Agent A then sends Agent B an I-Lang instruction chain:
::GENE{analysis_rules|conf:confirmed|scope:task}
T:conclusions_first
T:include_confidence_intervals
A:hedging_without_data⇒avoid
[READ:@SRC|path=quarterly_data.csv]
=>[STAT|by=region,product]
=>[TRND|period=Q]
=>[FMT|fmt=md]
=>[OUT]A2A handled the routing. I-Lang handled the instruction content. Each protocol does its own job.
Key differences at a glance
| Question | A2A | I-Lang |
|---|---|---|
| Does it help agents find each other? | Yes, via Agent Cards | No, not its scope |
| Does it define how agents behave? | No | Yes, via ::GENE{} declarations |
| Does it structure task instructions? | Task objects (high-level) | Verb chains (precise, step-by-step) |
| Does it work without infrastructure? | No, requires server endpoints | Yes, text-native |
| Is it open source? | Yes (Linux Foundation) | Yes (MIT license) |