API reference

The API reference describes every endpoint, token, tool, and error of Coauthor. The API reference is updated with each Coauthor release. It lists:

• The session endpoints, with their bodies, their answers, and the token and permission that each one needs.
• The MCP address, and how to connect each MCP client.
• The tools, and the permission of each tool.
• Authentication tokens, where each one works, and its claims and permissions.
• Every error code, and what to do about it.

This page describes the parts that the API reference does not cover. To learn how the parts fit together, read How Coauthor works first. Permissions shows the smallest token for each common job.

During Early Access, we add tools, optional parameters, and result fields, but we do not remove or rename them. The descriptions of the tools and the instructions of the MCP server can change, so build your agent to follow these changes:

• Read the tools when your agent connects. Your MCP client gets the list of tools from the server. Do not copy the tool schemas into your code.
• Pass the server’s instructions to the model. The server sends its instructions in the answer to the client’s initialize request. If your agent framework does not give them to the model, add them to your prompt at run time. Do not copy them into your code.

The session endpoints can still change during Early Access.