Elsewhere MCP server

Give any AI agent the ability to build in a persistent shared world.

Elsewhere is a protocol, not an app, and this is how an agent speaks it. Point Claude Code, Cursor, or anything else that speaks MCP at your Elsewhere account and it can find space, claim it, and build — through the same public endpoints and the same validator a stranger's HTTP request would hit.

Set up

1. Sign in to Elsewhere, open Developer API, and create a key. Tick the scopes the agent actually needs. read and build is the usual pair; add claim if it should be able to take new space for you. Leave transfer off unless you genuinely want it able to give your regions away.

2. Add it to your MCP config.

   Claude Code — ~/.claude.json (or .mcp.json in a project):

   {
     "mcpServers": {
       "elsewhere": {
         "command": "npx",
         "args": ["-y", "elsewhere-mcp"],
         "env": {
           "ELSEWHERE_API_KEY": "sw_live_...",
           "ELSEWHERE_API_URL": "https://elsewhere-api.onrender.com"
         }
       }
     }
   }

3. Ask for something.

   Find me somewhere quiet for an observatory, claim it, and build one.

Tools

| Tool | What it does | | --- | --- | | world_info | How big the world is, how much is claimed, the current version | | find_space | Search for unclaimed space matching a description, with reasoning | | check_space | Ask whether one exact volume is free, and what it overlaps if not | | describe_region | Owner, contents, size, and whether you may build there | | my_regions | What this key's account holds | | claim_region | Take unclaimed space. Free. Needs the claim scope | | build | Create, update and delete objects. The main one | | register_asset | Reference an external 3D file by content hash. Needs assets | | credits | Hosted-AI balance. Nothing these tools do spends it |

Two things worth knowing

Coordinates inside a region are region-local. 0, 0, 0 is the centre of your region at ground level, whatever its position in the world. Objects are positioned by their centre, so a 4m wall standing on the ground sits at y=2. This is not a quirk — it is what will keep the world free of floating-point drift when regions stop being twenty metres across.

Your tokens are yours. These tools cost nothing. When Claude Code drives Elsewhere, the model tokens are billed by your own provider on your own plan; Elsewhere only ever charges for its own hosted AI Builder, which is a different thing you did not use. The credits tool exists so an agent can say so accurately rather than guessing.

Running against your own world

ELSEWHERE_API_URL=http://127.0.0.1:4000 \
ELSEWHERE_API_KEY=sw_live_... \
npx elsewhere-mcp

Anything written to stdout that is not an MCP frame corrupts the session, so errors go to stderr. If the server exits immediately, that is where the reason is.