OnlyWorlds MCP Server

This endpoint speaks the Model Context Protocol (streamable HTTP). It lets AI assistants like Claude read and edit your OnlyWorlds worlds directly. You're seeing this page because you opened it in a browser; MCP clients connect to the same URL programmatically.

Connect from Claude Code

Just exploring? The schema tools need no account and no key:

claude mcp add --transport http onlyworlds https://www.onlyworlds.com/mcp

Your world: the same command, plus your credentials as headers:

claude mcp add --transport http onlyworlds https://www.onlyworlds.com/mcp --header "API-Key: <your world key>" --header "API-Pin: <your pin>"

Each command is a single line: paste it whole. Your world key lives on your world page. The PIN is needed for writes (and for reads on PIN-walled worlds); a read-only ow_r_ key needs no PIN. Claude Desktop and the Anthropic API's MCP connector work the same way with header credentials.

Tools

list_element_types · get_element_schema · search_schema	Schema reference. Works without any key
list_elements · get_element · search_elements · get_changes	Read your world (key required)
create_element · update_element · edit_links · bulk_apply	Edit your world (write key + PIN). Updates change only the fields you pass; link edits can be additive. There is no delete tool; deletion stays in the REST API and the portal.

The REST API serves the same data; interactive reference at /api/docs. Toolkit, guides and more at onlyworlds.github.io. The legacy /mcp/messages/ endpoint and npm client are retired.