The artifact tool's separate verbs collapse into one action parameter, with old names rewritten so existing prompts keep working.
The old artifacts tool verbs (upload_asset, read_file, read_asset, list_files, list_assets, list_types, describe_type, delete_asset) are replaced by a single action parameter on unified publish/list/read/delete tools. Calls made with the old verb names are rewritten via a regex table into the new phrasing (e.g. action: "upload_asset" becomes publish with asset: true, list_files becomes list with scope: "files"), and inputs/outputs are coerced between the legacy and new shapes so older prompts/skills keep working while the model is steered toward the new vocabulary.
The action: "list" action now accepts scope: "mine" (default), "shared", or "all", plus, when enabled, scope: "files", "assets", and "types". Publishing gains a new asset: true upload mode and a type_url describe mode, alongside a new delete action gated by t.deleteOn and an open action gated by t.openOn. A new validation branch also rejects a type argument unless the action is "list", clarifying that it names the type whose Artifacts to list, and that creating from a type should use type_url instead.
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
To keep thinking valid across a long session, treat the conversation as append-only. Add instructions with a [mid-conversation system message](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages) ([turn-s…models/fable-5-1/whats-new-fable-5-1 see the edit
The id of the `agent.tool_use` or `agent.mcp_tool_use` event this result corresponds to, which can be found in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list#beta_managed_agents_s…api/beta/sessions/events/list see the edit
Anthropic's documentation has since written up action, on List Events.