# Find a reference

Use this section to look up interface contracts, protocols and configuration fields. For system behavior and design constraints, see [Concepts and principles](../concepts/00-overview.md). For your first use, follow the [quick start](../getting-started/02-quickstart.md). If you have not decided which interfaces to call, choose an [application workflow](../workflows/01-overview.md) first.

| What you need | Entry point |
| --- | --- |
| SDK connections, HTTP authentication, response formats and errors | [SDK, HTTP and CLI conventions](../api/01-overview.md) |
| Server or client configuration fields | [Server configuration](../configuration/01-server.md), [client configuration](../configuration/02-client.md) |
| MCP tools, parameters and upload protocol | [MCP tools and protocol](../guides/06-mcp-integration.md); for client installation, see [Connect an MCP client](../agent-integrations/06-mcp-clients.md) |
| Resources, files and retrieval interfaces | [Resources](../api/02-resources.md), [file system](../api/03-filesystem.md), [content](../api/12-content.md), [retrieval](../api/06-retrieval.md) |
| Sessions, memory and skills interfaces | [Sessions](../api/05-sessions.md), [memory](../api/16-memory.md), [skills](../api/04-skills.md) |
| Administration, permissions and background state | [Admin](../api/08-admin.md), [ACL](../api/12-acl.md), [background tasks](../api/17-tasks.md), [Observer](../api/18-observer.md) |
| Consistency, isolation and processing completion | [Architecture](../concepts/01-architecture.md), [transactions and recovery](../concepts/09-transaction.md), [multi-tenancy](../concepts/11-multi-tenant.md), [queue state](../concepts/16-queue-lifecycle.md) |

The sidebar groups interfaces by the objects they operate on. Task guides remain in Build Applications or Deploy & Operate and link to the relevant references. For configuration steps, see [Configure models and services](../guides/01-configuration.md). For differences between integrations, see the [capability comparison](../agent-integrations/16-capability-reference.md).