# Helious Agent sign-in and A2A API

**Canonical:** https://apis.io/apis/helious-io/helious-io-agent-sign-in-and-a2a-api/  
**Provider:** Helious — https://apis.io/providers/helious-io/  
**Base URL:** https://api.helious.io  
**Documentation:** https://helious.io/developers/

Helious Agent sign-in and A2A API is one of 12 APIs that [Helious](https://apis.io/providers/helious-io/) publishes on the [APIs.io](https://apis.io/) network, described by a machine-readable OpenAPI specification. This API exposes 2 JSON Schema definitions. Tagged areas include Agent sign-in and A2A. The published artifact set on APIs.io includes an OpenAPI specification and 2 JSON Schemas.

OAuth 2.1 so an agent can act for a person without a pasted key, and the agent-to-agent endpoint for asking the desk a question in plain words.

## Operations (6)

| Method | Path | Summary |
|---|---|---|
| POST | `/a2a` | Ask the Helious desk a question, agent to agent |
| POST | `/mcp` | Model Context Protocol endpoint |
| POST | `/oauth/register` | Register your client (RFC 7591) |
| POST | `/oauth/token` | Exchange a code, or refresh |
| POST | `/oauth/revoke` | Revoke a refresh token (RFC 7009) |
| GET | `/oauth/userinfo` | Who this token belongs to |

## Machine-readable artifacts (4)

- **OpenAPI** — https://artifacts.apis.io/helious-io/openapi/helious-io-agent-sign-in-and-a2a-api-openapi.yml
- **JSONSchema** — https://artifacts.apis.io/helious-io/json-schema/helious-io-feed-item-schema.json
- **JSONSchema** — https://artifacts.apis.io/helious-io/json-schema/helious-io-envelope-schema.json
- **APIsJSON** — https://artifacts.apis.io/helious-io/apis.yml

## Other Helious APIs (11)

- [Helious Ask Helious API](https://apis.io/apis/helious-io/helious-io-ask-helious-api/)
- [Helious Boards API](https://apis.io/apis/helious-io/helious-io-boards-api/)
- [Helious Economic data API](https://apis.io/apis/helious-io/helious-io-economic-data-api/)
- [Helious News and feed API](https://apis.io/apis/helious-io/helious-io-news-and-feed-api/)
- [Helious Rates and curve API](https://apis.io/apis/helious-io/helious-io-rates-and-curve-api/)
- [Helious Reference API](https://apis.io/apis/helious-io/helious-io-reference-api/)
- [Helious Series API](https://apis.io/apis/helious-io/helious-io-series-api/)
- [Helious The Fed API](https://apis.io/apis/helious-io/helious-io-the-fed-api/)
- [Helious The squawk API](https://apis.io/apis/helious-io/helious-io-the-squawk-api/)
- [Helious Treasury auctions API](https://apis.io/apis/helious-io/helious-io-treasury-auctions-api/)
- [Helious Your key API](https://apis.io/apis/helious-io/helious-io-your-key-api/)

## Tags

Agent sign-in and A2A

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/helious-io/helious-io-agent-sign-in-and-a2a-api/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/helious-io/.