> ## Documentation Index
> Fetch the complete documentation index at: https://docs.semicola.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Changes and compatibility

> Changes to the v3 MCP endpoint, what counts as a breaking change, and how to stay compatible.

## How v3 changes

* **`tools/list` is the contract.** New tools and new optional fields can appear at any time. Read the
  schemas each session instead of hard-coding them.
* **Additive changes are not announced as breaking.** New optional input fields, new output fields,
  new enum values in outputs and new tools are all additive. Ignore what you do not understand.
* **Breaking changes are announced here first.** Removing a tool or field, making an optional input
  required, or changing a field's meaning gets an entry below with a date and a migration note.
* **REST and MCP evolve together.** Both act on the same records, so a new capability usually
  arrives in both.

## Changes

<Update label="2026-09-24" description="v3 preview">
  * The account-resolved endpoint `https://api.semicola.com/mcp/v3` is available to every buyer and
    seller account, with OAuth 2.1 (PKCE and dynamic client registration) and API keys. - Shared
    tools: `get_status`, `switch_account`, `search`, `get`, `open_page`, `get_delivery`. - Buyer tools
    for advertisers, campaigns, proposals, media buys, creatives and connections, plus their widgets.
  * Seller tools for the storefront, inventory sources, products, AI Business Rules, playbook, RFPs,
    materials and approvals, plus their widgets. - The [v3 Tool Catalog](/v3/tool-catalog) is
    generated from the same contracts the server validates against.
</Update>