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# credential()

Fetches the raw credential for a platform connection, for custom interactions the generated toolsets don't cover, such as driving a provider SDK or an MCP server yourself.

```typescript
import { credential } from '@mastra/connect'

const cred = await credential('c_yourconnectionid')

if (cred.type === 'oauth2') {
  startSdkSession(cred.accessToken)
} else if (cred.type === 'api_key') {
  startSdkSession(cred.apiKey)
} else if (cred.type === 'two_step') {
  startSdkSession(cred.token)
}
```

Returns: `Promise<ConnectionCredential>`, a discriminated union:

```typescript
type ConnectionCredential =
  | {
      type: 'oauth2'
      accessToken: string
      expiresAt: string | null
      secondaryAccessTokens?: Record<string, { accessToken: string; expiresAt: string | null }>
    }
  | { type: 'api_key'; apiKey: string }
  | { type: 'two_step'; token: string; expiresAt: string | null }
```

An OAuth2 credential can include `secondaryAccessTokens` for additional API audiences, keyed by the provider's connection-config field name. Each token has its own expiry.

Most applications should prefer [`tools()`](https://mastra.ai/reference/connect/tools), which keeps credentials entirely on the platform.

## Parameters

**connectionId** (`string`): ID of the connection to fetch credentials for.

**options** (`{ client?: ConnectClientOptions }`): Optional platform client overrides (accessToken, orgId, baseUrl, fetch). See ConnectClientOptions in tools().

## Credential handling

Returned credentials grant direct access to the provider account and bypass the proxy's guardrails. Don't log them or embed them in agent output. OAuth2 and `two_step` tokens can expire. Check their `expiresAt` fields, including those of secondary access tokens, and re-fetch the credential when needed.

Connections that use credential types this function doesn't support (for example basic auth) throw `unsupported_credential_type`.

## Errors

Throws `MastraConnectError` with a `code` property:

| Code                          | When                                                                                                                                                                                |
| ----------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `missing_access_token`        | No platform token configured                                                                                                                                                        |
| `connection_not_found`        | The connection doesn't exist or isn't accessible                                                                                                                                    |
| `unsupported_credential_type` | The connection's credential type can't be returned                                                                                                                                  |
| `unauthorized`                | The platform rejected the token (401/403)                                                                                                                                           |
| `platform_error`              | Any other platform response failure: a non-2xx status or an unparseable body. A network-level fetch failure isn't wrapped and surfaces as the runtime's own error, without a `code` |