# Direct API

> Use MCP Bond directly via bearer token authentication.

**MCP server URL**

```text
https://mcp.valency.io/
```

:::tip[For developers]
Use this guide to build an integration or connect an MCP client with a bearer token. For clients that support OAuth, use [one of the supported platforms](https://docs.valency.io/index.md#supported-platforms) or the [general MCP client guide](https://docs.valency.io/guides/other/mcp-client.md).
:::

## Connection details

| Setting | Value |
|---------|-------|
| Transport | Streamable HTTP |
| Authentication | Bearer token in the `Authorization` header |
| Request format | MCP JSON-RPC |

## Setup

1. Get your bearer token from your [Settings page](https://app.valency.io/settings) in the Valency app.

2. Configure your MCP client or SDK with the server URL above, the **Streamable HTTP** transport, and this header:

   ```text
   Authorization: Bearer YOUR_TOKEN
   ```

   Replace `YOUR_TOKEN` with your token. Clients may call this setting **Headers**, **Bearer token**, or **API token**; follow your client's configuration format. An MCP SDK handles initialization and protocol version negotiation for you.

3. Connect and call the `list_sources` tool. A returned source list confirms that authenticated tool calls work. You can then use the [MCP endpoint reference](https://docs.valency.io/reference/endpoints.md) to choose tools and their arguments.

:::tip[You're connected]
You received Valency's source list. Your integration can now call tools to search and analyze papers.
:::

## Optional: test the handshake with curl

To check your URL and token without configuring a client, send an initialization request:

```bash
curl --fail-with-body -sS https://mcp.valency.io/ \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  --data '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-11-25","capabilities":{},"clientInfo":{"name":"api-check","version":"1.0.0"}}}'
```

Expect a response containing `result.protocolVersion`, `result.capabilities`, and `result.serverInfo`. This checks initialization; use your MCP client or SDK to verify a tool call.

The example uses `2025-11-25`, a protocol version supported by Valency. If you implement MCP over raw HTTP, follow the [MCP lifecycle](https://modelcontextprotocol.io/specification/2025-11-25/basic/lifecycle): read the negotiated version, send `notifications/initialized`, and include the negotiated `MCP-Protocol-Version` header on subsequent requests.

## Troubleshooting

### Token rejected?

Check that you copied the full token and that your client sends `Authorization: Bearer YOUR_TOKEN` on every request. A successful health check does not verify your token. If authenticated requests still fail, [report the issue](https://docs.valency.io/help/reporting-issues.md) without including your token.

### Cannot reach the server?

Open the [health check](https://mcp.valency.io/health) in your browser, or run:

```bash
curl --fail-with-body -sS https://mcp.valency.io/health
```

The health check requires no token. A successful response confirms the health endpoint is reachable; it does not confirm that your integration can call MCP tools. If it fails, check your network and [report the issue](https://docs.valency.io/help/reporting-issues.md).

### Need help?

See [Troubleshooting](https://docs.valency.io/help/troubleshooting.md) or [report an issue](https://docs.valency.io/help/reporting-issues.md) with your client or SDK name, version, and the error you received.