---
title: Versions and deprecation
description: How Siglata versions its agent interfaces, what counts as a breaking change and how much notice you get before a removal.
sidebar:
  order: 9
---

Nothing is deprecated today. This page says how Siglata gives notice when that changes.

## Where the version is

- **MCP endpoint:** the version is in the URL, `https://www.siglata.com/v1/mcp`.
- **MCP server:** `serverInfo.version` in `initialize` and the [server card](https://www.siglata.com/.well-known/mcp/server-card.json) carry the server version as `MAJOR.MINOR.PATCH`.
- **Public search:** the [OpenAPI description](https://www.siglata.com/nlweb/openapi.json) carries its version in `info.version`.

## What is breaking

We raise the URL version and the server `MAJOR` when:

- an MCP operation is renamed or removed;
- a required parameter is added, or a parameter or result changes type or meaning;
- an OAuth scope stops granting the access it granted.

Not breaking: a new operation, a new optional parameter, a new field in a result or a better error message. Ignore fields you do not recognize.

## Notice before removal

1. The change is announced in this documentation and the old version keeps working next to the new one.
2. Every response from the old version carries the `Deprecation` header ([RFC 9745](https://www.rfc-editor.org/rfc/rfc9745)) and the `Sunset` header ([RFC 8594](https://www.rfc-editor.org/rfc/rfc8594)) with the removal date.
3. Removal comes at least 90 days after the announcement.

## Usage limits

When a rate limit refuses a call, the response is `429` with a `Retry-After` header, in seconds. Today this applies to the authentication routes under `https://www.siglata.com/auth`.