Why Quater Exists
This page explains the problem Quater is built around before it explains the API.
The Shift
Most backend frameworks grew up around the same shape of software: a backend serves a frontend, and people use that frontend to do work.
That shape still matters. People still need apps, dashboards, admin panels, and normal APIs. But AI agents are becoming another caller of backend systems. They need to read data, perform operations, and help run software.
The awkward part is the interface. A screen is a good interface for a person. It is a slow and fragile interface for an agent. If an agent has to click through menus and forms to do backend work, the system becomes harder to trust and harder to operate.
The Problem
Teams usually patch around this with extra code:
- one endpoint for the app
- one wrapper for an AI tool
- one script for internal operations
- one private shortcut for support or incident work
Those paths start close together, then drift. One path gets new validation. One path keeps old auth. One path returns a slightly different shape. One path skips the check that the public API depends on.
That drift is the real problem. It makes the backend harder to reason about.
What Quater Is Trying To Make
Quater is trying to make the backend itself a safe operating surface.
You still build normal APIs for people and services. When an operation should also be callable by an AI agent or operator, you opt it into that surface. The operation keeps one handler, one binding model, one route-level auth policy, and one place where the application logic lives.
The outside access paths stay separate because they have different security needs. MCP has its own auth. CLI has its own auth. Sensitive actions can require approval for one exact argument set.
The result should feel boring in the right way: a normal Python backend that is also ready for agents and operations.
What Quater Is Not Trying To Do
Quater is not trying to replace Django/FastAPI/Flask. It does not ship an ORM, migrations, templates, a user model, or an admin site.
Quater is also not trying to make every backend action available to agents. The default model is opt-in. You choose which operations become tools or actions.
What Can Go Wrong
MCP tools require mcp_auth : Quater refuses to expose tools without MCP transport auth. Add mcp_auth=... to Quater(...).
CLI actions require cli_auth : Quater refuses to expose CLI actions without CLI transport auth. Add cli_auth=... to Quater(...).
Also See
- HTTP, MCP, and CLI Surfaces: how the access paths fit together.
- Auth Model: where the auth boundaries run.
- MCP Tools: how agents discover and call route-backed tools.