Connect Claude Code

Claude Code can talk to Creator directly: one command adds the running editor as an MCP server, and from then on you can ask about the open map and propose changes to it from your terminal. This page is the whole setup.

You bring your own Claude account. Creator holds no key of its own, makes no call to any service, and sends no telemetry.

What you are connecting to

While Creator is open it can run a small server of its own, and three facts about it are worth knowing before you start:

• It listens on 127.0.0.1 only. That address is your own machine and nothing else. No port is opened to your network or to the internet.
• It exists only while Creator is open. Close Creator, or press the stop button, and the server is gone.
• Nothing about your map leaves the PC except what you yourself send into your own Claude session.

Every change waits for you. Claude can read the open map freely, but a tool that would change something never acts on its own: it returns a proposal, Creator shows a confirm card, and nothing moves until you click it. There is no setting that turns that off. The one place a single click covers more than one change is a Build from Reference session in the prefab workspace, which you open for one pack and end with STOP BUILDING.

Claude Code is the one client that speaks to Creator’s server directly, so it needs no extra program installed. (Claude Desktop cannot, which is why it has a page of its own.)

The Crucible Launcher’s Local Agent

There is one other way in: the Crucible Launcher’s Local Agent. While the Local Agent is installed, pressing Play on Creator in the launcher starts Creator with its server already on, on this PC only, with a new token each time. You do not click START or copy a token for it, and the steps on this page are not needed for it.

• It connects only to a Creator the launcher started. Start Creator any other way and its server stays off until you click START.
• Every change still waits for you, on the same confirm card as any other client.
• Preferences > CONNECT shows the server running, and STOP (KILL SWITCH) shuts it, the same as for a server you started yourself.

Step 1: start Creator’s server

1. Open Creator.
2. Open Preferences and choose the CONNECT tab. On the start screen, PREFERENCES is the button beside HELP at the bottom left; with a map open, it is EDIT > Preferences…. You do not need a map open to connect.
3. Click START.

The tab now shows the port it is listening on (8790 unless you changed it) and this session’s token, which is the password Claude Code uses to talk to it.

Step 2: add Creator to Claude Code

The CONNECT tab shows the exact commands, with the live port and token already in them, and a COPY button that puts both on your clipboard. They look like this:

claude mcp remove creator --scope user
claude mcp add --transport http --scope user creator http://127.0.0.1:8790/mcp --header "Authorization: Bearer <token>"

Run both in a terminal, in that order, with <token> replaced by the token from Preferences > CONNECT (the COPY button does that for you). The first line removes an entry an earlier Creator session left behind, because claude mcp add refuses a name it already has; on a first setup it only says there was nothing to remove.

Then type /mcp in Claude Code to connect.

A Claude Code session that is already running does not notice a new or changed entry until you do.

Where the entry is saved is set by --scope, and both lines use --scope user, so the remove always finds the entry the add made:

Scope	What it means
--scope local	The default. Only this project, only you.
--scope user	All of your projects, still only you. Usually what you want for Creator.
--scope project	Written to .mcp.json in the project and shared with anyone who has the repository.

Creator’s token changes every time its server restarts, so do not use --scope project for it: that writes a credential into a file other people can read, and it will be stale by tomorrow anyway.

Step 3: check that it worked

1. Run /mcp inside Claude Code. It lists each server with its health, and creator should read connected.

2. With a map open in Creator, ask:

   What map is open in Creator right now?

Claude calls the get_map_summary tool and answers with the map’s size, its seed, and how many prefabs it holds. That answer means the connection works end to end.

Useful commands while you set this up:

claude mcp list            # every server you have added, and its health
claude mcp get creator     # what was stored for this one
claude mcp remove creator --scope user  # remove it again

What “confirm in Creator” looks like

Ask for something that changes the map and Claude does not change it. Instead:

1. Claude’s answer says it has proposed the change.
2. Creator shows a confirm card describing exactly what would happen, and naming the client that asked for it (the name that client gives itself, such as claude-code), so with two clients connected you can tell whose request it is.
3. You click to accept or dismiss it. Dismissing it is a real refusal, and Claude is told so.
4. Long work, such as generating a world, then runs as a job. Claude reads its progress with get_job rather than waiting on the call, so nothing times out.

So keep Creator’s window where you can see it: a proposal that nobody clicks is a request left hanging.

Is the card up? Taking a request back

Claude can see enough of your screen to know whether you can answer it, and no more:

• Which screen you are on. get_map_summary says whether Creator is on its start screen, loading, showing the generation screen, in the editor with a map open, or in the prefab workspace, and whether a map is fully open. After FILE > Unload Map it says that no map is open.
• Whether its request is waiting for you. The same answer, and get_job, say whether a request is still waiting for your click, how many seconds are left before it expires (an unanswered card expires), and whether its confirm card is actually on screen.

It sees nothing else: not the names of Creator’s windows or panels, and nothing about how Creator is built.

Taking a request back. If Claude changes its mind while a card is up, it can withdraw its own request with the cancel tool. The card closes, Creator tells you the request was taken back, and nothing changes. Cancel needs no click, because all it can do is take a request back. It never stops work you have already approved: a generation you clicked GENERATE on runs to the end.

Standard Mode and Creator Mode from Claude

The recipe Claude builds with you is in one of the two modes the Procedural Generation panel has.

• Standard Mode is Rust’s own generation for a size and a seed, with the game’s own percentages and filters. A new recipe starts here.
• Creator Mode is everything beyond that: generating on a heightmap of your own, leaving monuments out, pinning a monument to an island, and bridges with one road around a group of islands. Ask for any of those and the recipe switches to Creator Mode on its own, and the tool’s answer tells Claude it did, so Claude can tell you.

Claude can see which mode the open map and the draft are in, and it can set the mode directly if you ask.

Choosing monuments. Claude can list every monument your Rust content carries, one row per monument with its family, and leave any of them out of the recipe, or a whole family. It means exactly what unchecking the monument in the panel means: a monument left out is never placed, and the ones left in are still placed by Rust’s own rules.

A heightmap from a file. Claude can point the recipe at a .raw heightmap, but only one inside Creator’s own folders: the Creator maps folder in Documents, the folder of the map that is open, the recipe library, or Creator’s data folder. A path anywhere else is refused, and the refusal names the folders. To use a file from somewhere else, move it into one of them, or import it yourself in the panel’s LAND section.

The confirm card. A Creator Mode generation’s card carries the CREATOR MODE badge and opens with the same sentence the panel’s own confirm does, “Creator Mode: this map will not be a vanilla generation.”, followed by the land, how many monuments are left out, how many are pinned, and whether bridges are on. A Standard Mode card is unchanged.

Naming monuments

Claude can use a monument’s name from the list (for example Launch Site) in any of the six monument fields of a recipe. A name that matches no monument is refused on the spot, with the closest names, so a misspelt monument is caught before anything is generated. What each list matches:

Field	What an entry can be	What it does
monuments.exclude	a monument’s name, file name or key, or a whole family as family:<Family Name>	Leaves those monuments out and nothing else (Creator Mode).
monuments.blacklist	a monument’s name, or any part of a prefab’s key	Leaves out every prefab whose key contains it, monument or not.
monuments.whitelist	a monument’s name, or any part of a prefab’s key	Places ONLY prefabs whose key contains an entry, so it also removes rocks, trees and road furniture.
monuments.set	a monument’s name, file name or key	Only these monuments: no other monument is placed, and everything that is not a monument generates normally.
monuments.required	a monument’s name, file name or key, or a whole family as family:<Family Name>	The map must have it: a generation that does not place it stops early and saves nothing, in either mode. A name two monuments share is refused, with the names that tell them apart. See Required monuments.
monuments.names	monument=Map Name, the monument as a name, file name or key	Gives that monument your own Map Name on the in-game map. Every copy of that monument the map places gets the name, in either mode.

monuments.set limits monuments only. A map limited to four monuments by the set has only those four monuments, and still has its rocks, jungle trees, road furniture and tunnels. The whitelist is the one that filters every prefab. To keep a few monuments out instead, ask Claude for the exclude list or the blacklist.

A recipe that would place no monument is refused before the card. If the monument lists leave nothing Rust can place on a map of the recipe’s size (every monument in the set is too big for the map, the set or the whitelist names no monument, or the exclude list and the blacklist leave them all out), generate and replay refuse it with MONUMENTS_SET_EMPTY, say which list did it and how to fix it, and show no confirm card. With no map open, get_validation checks the recipe Claude is editing and reports the same finding.

A recipe that requires a monument it also rules out is refused the same way. Requiring a monument the recipe leaves out, keeps outside the set, counts to zero, filters with the blacklist or whitelist, or one Rust does not place on a map that small, is refused before the card with a MONUMENT_REQUIRED_... finding that names the monument and the fix.

Several maps from one request

Ask for several maps and Claude passes generate a list of seeds, or a count of random ones, up to 20. It is still one confirm card, which says how many maps and that each kept one is saved with a picture into a new folder in your maps folder, and one job. get_job then lists a row per seed: kept, stopped (a required monument was not placed), faulted, refused (Creator could not start that run, and says why) or canceled, the monuments each kept map holds, and its file name. The folder is always Creator’s own choice inside your maps folder; Claude cannot name another. Generating several maps describes the queue itself.

Reading the prefab workspace

With a pack open in the prefab workspace, Claude can read it. None of these change anything, so none of them shows a card:

Tool	What Claude learns
get_workspace	Whether the workspace is open, the pack’s name, each piece’s prefab and where it stands, and each reference model or image with its size in meters and whether it has loaded; for a picture, where it stands and which way it faces
get_reference_shape	A loaded reference model cut into blocks of a size Claude picks: its size, how much of each height is filled, its large flat faces, its materials (name, color and texture name), and the boxes that would fill it, each with its material and color and marked when it has nothing under it
search_pieces	Rust’s prefabs by name, folder, size or material (stone, concrete, wood, metal, glass or other), each with its size in meters and its material
preview_pieces	A picture of up to six prefabs side by side at their real sizes, so Claude can see what they look like
get_coverage	How much of a reference model the pack’s pieces fill, which heights still have gaps, and which pieces stick out of it; for a picture, how much of what it shows the build covers seen the way the picture faces, and whether the build stands in front of it
render_workspace	A picture of the pack from the front, back, left, right, top or a corner, with the reference shown or hidden, of a 3D model reference alone in its own colors, or of the build plan as plain boxes; it can outline what you have selected in orange, in its picture only. Your own view does not move.
compare_reference	The build pictured from its reference’s own view, beside the reference, with a picture of the difference, how well the outlines overlap, where they differ most and where their colors differ. Your own view does not move.
get_selection	What you have selected in the workspace, so “this” in your chat means something: each piece with the part of the plan it builds, its size and where it stands, the lines of your requirements it affects, and the pieces touching it or resting on it

Sizes come from your own Rust files. Creator measures a prefab the first time something needs it, so a search can list a piece as unmeasured. Claude can ask Creator to measure the listed ones and search again. Nothing in your pack or your map changes while it does; the prefab browser’s preview may show a piece loading.

A reference image has no shape to read, only its size, where it stands and what it shows. A reference that has not finished loading is refused until it has.

Building in the prefab workspace

These tools let Claude plan, build and check in the open pack, for Build from Reference:

Tool	What it does
start_build_session	Shows the BUILD FROM REFERENCE card. When you click ALLOW, Claude can build in that one pack without a card for each change, until you press STOP BUILDING, save the pack, close it, or switch to another pack or the map.
set_build_plan	Keeps Claude’s plan for the build (its parts, their sizes and materials, doors and windows, what holds each part up, and what Claude had to guess) for the build session, with each thing you asked for in your own words, and says what Creator found wrong with it. The guesses and your requirements show in the DOCUMENT panel. It changes nothing in the pack.
get_build_plan	Reads that plan and your requirements back.
edit_pieces	Places, moves, resizes and removes pieces of the open pack, in batches. Each batch is one Ctrl+Z. If any change in a batch is refused, nothing in it is applied. Each piece can name the part of the plan it builds. When you have pieces selected, it tells Claude every piece outside your selection the batch changed, and how.
check_build	Checks the pack for pieces with nothing under them, pieces barely held up, overlaps and near gaps, compares it with the plan, points out any part of a 3D model reference with nothing under it, and measures each of your requirements against the build: met, not met and by how much, or not measurable and why. It changes nothing.

Creator also offers a prompt that walks Claude through a whole build: type /mcp__creator__build_from_reference in Claude Code, optionally followed by what to build.

The token changes every time the server starts

The token changes every time the server starts; copy the new one.

After you restart Creator, run the two lines from Step 2 again with the new token (the CONNECT tab’s COPY gives you both, remove first), then type /mcp in your Claude Code session. A session that is already running does not notice a server that was removed and added again, or a Creator that restarted, until you do.

The recipe Claude is building with you lives in Creator and is gone when Creator closes. Ask Claude to export it first (export_recipe), or save it to your recipe library, if you want to keep it.

The stop button

Preferences > CONNECT > STOP shuts the connection, and every connected client is cut off. Use it whenever you want the door shut, and remember that closing Creator does the same thing.

The CONNECT tab shows a log of recent calls. Your map’s data is not in it.

Troubleshooting

/mcp shows creator as needing authentication. Claude Code says that when the server answers 401, which here means the token is wrong. Creator has restarted since you added it, so the token it was given no longer exists. Run the two lines from Step 2 again with the current token (remove first), then type /mcp.

/mcp shows creator as failed to connect. Nothing is listening on that port. Creator is closed, its server was never started, or it is on a different port. Open Preferences > CONNECT and check that it says it is listening, on the port your claude mcp add line named.

Calls fail with 403. Check that the URL in the add line is exactly http://127.0.0.1:<port>/mcp and that no proxy rewrites it.

Creator will not start its server: “port in use”. Something else on your PC already holds port 8790. Type a different port into the Port field in Preferences > CONNECT, click START, and add the server again with the new port in the URL.

A tool’s answer is cut short. Claude Code truncates a large tool result (about 25,000 tokens by default, MAX_MCP_OUTPUT_TOKENS). Creator’s catalogs page rather than dump, so ask for the next page, or narrow the question.

Creator says a tool cannot run right now. Some tools need a map open, and none of them will start while a generation is still running. The tool’s own answer says which of those it is.

You can generate as many times as you like in one session. Generating while a map is already open replaces it, so that confirm card says in as many words that an unsaved world is destroyed: save first if you want to keep what is on screen.

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Claude Code’s own documentation: Connect Claude Code to tools via MCP.