# What AIP Is

AIP is a protocol for running useful work across agents and applications when a
simple tool call is not enough.

It answers five practical questions:

1. **What can this system do?** A manifest publishes typed capabilities,
   resources, supported transports, and security requirements.
2. **Who is asking?** A trusted identity context preserves the human, service,
   tenant, external account, and delegated authority involved in the request.
3. **What is allowed to happen?** A capability contract declares side effects,
   data sensitivity, retry safety, approval rules, and transaction behavior.
4. **What is happening now?** Every action has a durable lifecycle that can be
   queried, streamed, cancelled, resumed, and recovered.
5. **What actually happened?** Events, receipts, audit records, and transaction
   state provide operational and compliance evidence.

## The Problem AIP Solves

Applications already expose APIs, tools, webhooks, queues, and agent-specific
protocols. Those interfaces are useful, but they usually describe only how to
send a request. They do not give every participant the same answers for
approval, retries, cancellation, tenant boundaries, delegated authority, or a
provider outcome that is temporarily unknown.

AIP adds a shared semantic layer. A restaurant booking, refund, CRM update, or
agent delegation becomes a typed action with an identity, policy, lifecycle,
and evidence trail. The underlying application remains responsible for its
domain logic; AIP makes that logic interoperable and governable.

## AIP Is One Protocol, Not Several Product Branches

AIP has one native semantic model. Products join it through connectors, and
existing protocols join it through compatibility profiles.

- A **connector** maps a product's real API and events to AIP capabilities and
  lifecycle events.
- A **compatibility profile** maps another protocol to the same AIP semantics.
- A **transport binding** carries native envelopes over HTTP, NATS, SSE, or
  WebSocket without changing their meaning.

There is no separate enterprise edition of the wire model. A simple read-only
tool can publish a small capability contract, while a payment or identity
operation publishes the full approval and transaction contract. Both are AIP.

## Relationship to MCP

MCP is a first-class compatibility profile, not a second runtime. Existing MCP
clients can discover and call AIP-backed tools through MCP stdio or Streamable
HTTP. The AIP gateway translates those calls into native actions and projects
native lifecycle data back into MCP responses, notifications, and tasks.

MCP remains useful for broad client compatibility. Native AIP is the stronger
contract when a workflow needs durable state, enterprise identity, approval,
transactions, delegation, or operational query APIs.

## Relationship to Agent-to-Agent Protocols

AIP models delegation natively as a parent-child action graph. An A2A-facing
endpoint may be exposed by a compatibility profile, but A2A objects do not enter
the AIP semantic core. The same separation applies to product-specific task and
conversation models.

## Who Uses AIP

| Reader | What AIP provides |
|---|---|
| Application developer | One typed contract for calling tools and workflows |
| Agent developer | Discovery, streaming, cancellation, and remote delegation |
| Product integrator | A connector SDK with consistent identity and error rules |
| Platform team | Durable execution, recovery, policy, and tenant isolation |
| Security team | Trusted identity, least privilege, approvals, and replay control |
| Operations team | Query APIs, metrics, events, receipts, and audit evidence |

## What AIP Does Not Do

AIP does not replace an application's business logic, database, authorization
source, or secret manager. It does not make a non-idempotent provider exactly
once, and it does not make an untrusted identity claim trustworthy. A production
deployment must connect AIP to real identity, policy, storage, and provider
boundaries.

Next, run the [Quickstart](quickstart.md) or read [How AIP Works](how-aip-works.md).