> For the complete documentation index, see [llms.txt](https://docs.orbitfin.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.orbitfin.ai/orbit-api-reference/a2a/2.-agent-builder-a2a-setup.md).

# 2. Agent Builder A2A Setup

Step 1: Obtain API Key

The caller needs an API Key under an Agent Builder account as an identity credential — all actual A2A calls must carry it.

Step 2: Confirm the A2A Service Address

Agent Builder's A2A service address: <https://studio.orbitfin.ai>[/builder/a2a](https://orbit-api-agent.orbitfin.ai/builder/a2a)

Step 3: Read the Agent Card and Verify Connectivity

The Agent Card is a publicly readable "business card" document that can be accessed without authentication. It is used to confirm whether the service is reachable and what capabilities are currently available: <https://studio.orbitfin.ai>[/builder/a2a/.well-known/agent-card.json](https://orbit-api-agent.orbitfin.ai/builder/a2a/.well-known/agent-card.json)

The returned content includes Agent Builder's name, feature description, supported authentication methods, and the complete list of capabilities (Skills) — if you can successfully obtain this document, it means this step is configured correctly.

Authentication Methods

The Agent Card declares two optional authentication methods (satisfying either one is sufficient):

| Method       | Usage                                               |
| ------------ | --------------------------------------------------- |
| API Key      | Request header `X-API-Key: YOUR_API_KEY`            |
| Bearer Token | Request header `Authorization: Bearer YOUR_API_KEY` |

Calls without a valid credential will be rejected; reading the Agent Card itself does not require authentication.