A2A already has Task status — why also DCP?

A2A Task status answers whether one delegated job finished (submitted, working, completed, failed). It has no Decision, Finding, ArchitectureImpact, Milestone, or Dependency entity, so it cannot record why the project changed. DCP models exactly those eight coordination entities, and a DCP event can travel inside an A2A Message Part or Task metadata field.

Do DCP and A2A compete?

No. A2A is a transport and execution protocol for delegating and tracking tasks between agents. DCP is a payload vocabulary for project-coordination semantics. They operate at different layers and are designed to stack, not substitute for each other.

Can a DCP event be sent over A2A?

Yes. Because DCP is transport-neutral, a DcpMessage envelope can be embedded as a Part inside an A2A Message, or attached as Task metadata, letting an A2A-based system carry structured coordination facts alongside its normal task lifecycle.

DCP vs. A2A

DCP and A2A solve different problems that both start with “agent-to-agent.” A2A (Agent2Agent Protocol, now under the Linux Foundation) is a wire protocol for delegating and tracking a task on a remote agent. DCP is a payload vocabulary for recording project-coordination facts — decisions, findings, dependencies — that no task-status field captures. They compose: a DCP event can ride inside an A2A message.

The money question

“A2A already gives me a Task lifecycle and status — why also DCP?”

Because A2A’s Task answers a narrower question than it looks like it does. A2A’s Task object (id, contextId, status, artifacts, history, metadata) and its nine-state TaskState enum (SUBMITTED, WORKING, COMPLETED, FAILED, CANCELED, INPUT_REQUIRED, REJECTED, AUTH_REQUIRED, UNSPECIFIED) tell you whether one delegated unit of work is done. That is genuinely useful and DCP doesn’t attempt it — DCP has no execution model at all.

But A2A’s complete entity list — Task, Message, Part, Artifact, AgentCard, Role, TaskStatus, Extension — has no first-class Decision, Finding, ArchitectureImpact, Milestone, or Dependency. If your agent decided to use Postgres over MongoDB, found a race condition in review, or determined that a change impacts the auth module’s architecture, A2A gives you nowhere structured to put that except free text in a Message or an untyped metadata blob. There’s no shared vocabulary another agent can parse it against.

A2A’s Task tells you whether a delegated job finished; DCP tells you why the project changed.

Side-by-side

	DCP	A2A
Layer / purpose	Semantic payload vocabulary for project-coordination events	RPC-style protocol for delegating and tracking tasks between opaque agents
What it models	8 closed entity types: Project, Task, Dependency, ArchitectureImpact, Decision, ReviewRequest, Finding, Milestone	Task, Message, Part, Artifact, AgentCard, Role, TaskStatus, Extension
Task/job status	Not modeled — DCP’s `Task` entity records coordination facts about a task (e.g., it was created, blocked, completed), not a live execution state machine	Core feature — 9-state `TaskState` enum tracks one delegated unit of work end to end
Decisions & findings	First-class `Decision` and `Finding` entities with dedicated schemas	No equivalent — would need to be embedded as free text in `Message`/`metadata`
Architecture impact	First-class `ArchitectureImpact` entity	Not modeled
Milestones & dependencies	First-class `Milestone` and `Dependency` entities, plus a closed 8-term `rel` vocabulary (`blocks`, `caused_by`, `supersedes`, etc.)	No coordination-relationship vocabulary; `Task` has no native concept of blocking another `Task`
Trust/identity	None by design — “DCP carries no trust”; a DCP message is untrusted data	`AgentCard` covers capability discovery and security-scheme negotiation for the agent being called
Transport	Transport-neutral — no wire protocol of its own	Defines the wire protocol: JSON-RPC 2.0 over HTTP, with SSE streaming
Governance / status	Apache-2.0 (code/schemas) + CC-BY-4.0 (docs); 8 entities, 14 JSON Schemas, 70 passing tests, 25 conformance cases, as of 2026-07-03	Linux Foundation project (donated by Google, announced 2026-06-23); Technical Steering Committee with AWS, Cisco, Google, IBM Research, Microsoft, Salesforce, SAP, ServiceNow; current release v1.0.1
Relationship	Complementary — designed to be carried by a transport	Complementary — designed to carry payloads, including a DCP event

Both are fair to describe as narrow by design. A2A explicitly scopes itself to task delegation and interoperability between agents that don’t share internal state; it was never meant to hold a project’s decision history. DCP explicitly refuses to touch transport, execution, or trust. Neither project overreaches into the other’s territory, so there’s no strawman here — just two protocols with disjoint job descriptions.

Do agents that use A2A still need DCP?

Yes, if the agents need to record project-level facts that outlive a single delegated task. A system built entirely on A2A can tell you that Agent B accepted a task, worked on it, and completed it — a clean, auditable execution trail. What it can’t tell you, without inventing ad hoc conventions, is why the project’s direction changed as a result: what was decided, what was found, what got blocked, what shipped as a milestone. That’s a different kind of record, and it’s the one A2A’s spec authors left as “an exercise for the caller.”

The two protocols are not a fork in the road — they stack. A DCP event fits naturally inside an A2A Message Part or a Task’s metadata field, the same way it could ride inside a CloudEvents envelope or a webhook body. Read more on why a shared coordination vocabulary matters even when a delegation protocol is already in place in why a coordination vocabulary, and see the full entity list in the entity reference. DCP’s refusal to touch identity or delivery is covered in DCP carries no trust. For the comparison against a tool-and-context protocol rather than a task-delegation one, see DCP vs. MCP, or browse the full set of comparisons on the comparison hub.

By InterIP Networks · Last updated 2026-07-01.