RPG Maker XP MCP Server

Build RPG Maker XP games by describing what you want.

"Make a healing potion that restores 200 HP and costs 150 gold." "Create a 40×30 forest map with a pond in the north-east, then show it to me." "Find every NPC on map 3 whose dialogue mentions the king."

This is an MCP server that reads and writes an RPG Maker XP project's .rxdata files directly — actors, skills, items, maps, events, scripts and system data — and renders map previews to PNG so you can see what was built without opening the editor.

It talks to XP's native Ruby 1.8 Marshal format. Nothing is exported, converted, or kept in a side file: it edits your real project, and the editor opens the result normally.

⚠️ Read this before your first run

1. Close the RPG Maker XP editor while the server is running. The editor holds all data files in memory and rewrites every one of them when you save. If it is open, it will overwrite anything this server changed. This is the single most common way to lose work.

2. Back up your project first. Copy the whole Data/ folder somewhere safe. Do this even though the server takes its own backups, because:

3. The automatic backup is not version history. Before its first write to a file in a session, the server copies the original to Data/.mcp-backup/. That is one .bak per file per session — the next session overwrites it. It protects you from the last thing you did, not from something you broke a week ago. If your project matters, put it in git.

4. Test your game after changes. A file can be structurally valid and still be wrong for your game.

Related MCP server: DMCP

What is MCP?

The Model Context Protocol is a standard way for AI assistants to use external tools. This server is not a chat program and has no interface of its own — it is a backend that an MCP client connects to.

You need one of those clients. Common choices:

• Claude Code — terminal-based

• Claude Desktop — desktop app

• Open WebUI, Cursor, Windsurf, or any other MCP-capable client — including local models through Ollama (see below)

If you have never used an MCP client, start with Claude Desktop; the Configuration section has a copy-paste config.

Requirements

The RTP (the default tiles, autotiles, character sprites and audio) is read from your own installation at runtime. This project does not bundle or redistribute any Enterbrain assets.

Does it work with Pokémon Essentials?

Structurally, yes — Essentials games are RPG Maker XP projects, and every tool here operates on standard .rxdata. Two honest caveats: Essentials layers its own conventions on top of the engine (its own data files, a very large Scripts.rxdata, PBS text files) which this server knows nothing about, and its projects are big enough that you should be especially sure about backup point 2 above. Reading, map work and database edits behave normally.

Installation

The published package ships prebuilt, so there is no build step. Most clients can launch it on demand with npx.

npm install -g rpgmaker-xp-mcp

git clone https://github.com/SerifeusStudio/rpgmaker-xp-mcp.git
cd rpgmaker-xp-mcp
npm install
npm run build

Then use node with the path to dist/index.js as the command in the configs below.

Configuration

Point the server at your project with RPGMAKER_PROJECT_PATH — the folder containing Game.rxproj and Data/. If your RTP lives somewhere unusual, also set RPGMAKER_RTP_PATH; it defaults to the Steam RPG Maker XP install.

Claude Code

claude mcp add --scope user rpgmaker-xp \
  --env "RPGMAKER_PROJECT_PATH=C:\path\to\your\project" \
  -- npx -y rpgmaker-xp-mcp

Claude Desktop

%APPDATA%\Claude\claude_desktop_config.json:

{
  "mcpServers": {
    "rpgmaker-xp": {
      "command": "npx",
      "args": ["-y", "rpgmaker-xp-mcp"],
      "env": {
        "RPGMAKER_PROJECT_PATH": "C:/path/to/your/xp/project"
      }
    }
  }
}

Restart the client, then check it connected by asking for something read-only:

"List the actors in my project."

If you get names back, you are set up. See SETUP.md for troubleshooting.

Using a local model via Ollama

The server speaks standard MCP over stdio, so it works with any MCP client, not only Claude. Ollama has no MCP client of its own yet, so a local model reaches it through a bridge.

Open WebUI has native MCP support via mcpo, an OpenAPI proxy. Save the same mcpServers block as mcpo.json, then:

uvx mcpo --port 8000 --config mcpo.json

Register http://localhost:8000/rpgmaker-xp in Open WebUI as a tool server.

Terminal: ollmcp connects MCP servers straight to a local Ollama model.

Pick a model with solid tool calling (a recent Qwen or Llama instruct model). Smaller models struggle to chain several calls reliably, which matters here — map authoring is inherently multi-step.

What it will not do

Worth knowing before you install:

• XP only. It does not read VX, VX Ace, MV or MZ projects. Their data formats are different (.rvdata, .rvdata2, JSON).

• It does not generate art or audio. It can import, classify and validate graphics you already have; it cannot draw them.

• It does not write RGSS scripts for you beyond storing what it is given — it manages Scripts.rxdata as data, and correctness is on you and your model.

• It cannot run your game or test it. render_map shows a static layout preview, not gameplay.

• It does not know about Pokémon Essentials' own systems (PBS files, its plugin conventions, its data classes).

Available tools (65)

get_actors · get_actor · update_actor · create_actor · search_actors

XP actors use a parameters Table (6×100 — MaxHP, MaxSP, STR, DEX, AGI, INT per level) rather than MZ-style traits. create_actor generates linear growth curves by default. Equipment slots are weapon_id and armor1_id–armor4_id (shield / helmet / body / accessory).

get_items · get_weapons · get_armors · get_skills · update_item · search_items · create_weapon · create_armor

create_weapon/create_armor append to Weapons.rxdata/Armors.rxdata with editor-default fields (override any). Armor kind: 0=shield, 1=helmet, 2=body, 3=accessory.

get_skill · create_skill · create_damage_skill · create_healing_skill · create_state_skill · update_skill · search_skills

XP has no damage formulas. Damage is power scaled by stat-influence rates (atk_f/str_f physical, int_f magical) and reduced by the target's pdef_f/mdef_f. Negative power = healing. There is no create_buff_skill — XP has no buff system, use states.

Scope: 0=none, 1=one enemy, 2=all enemies, 3=one ally, 4=all allies, 5=one ally (HP 0), 6=all allies (HP 0), 7=user.

get_map · get_map_infos · get_map_events · get_map_event · update_map_event · create_map_event · create_transfer_event · search_map_events · add_event_command · add_show_text

Maps live in Data/MapXXX.rxdata. get_map summarises the tile Table unless includeTiles: true. Events are a hash keyed by event ID.

add_show_text handles XP's message structure (first line = code 101, continuations = 401, 4 lines per box). XP specifics: code 101 carries text directly (unlike VX+); choice text is stored redundantly in both the 102 array and the 402 branches and must stay in sync; move routes are 209/509.

create_transfer_event wires two maps together and validates both endpoints exist and are in bounds before writing. Run validate_connectivity afterwards. The full 110-code table is in research/event-commands.md.

get_map_design_guide · get_map_size_advisory · create_map · get_map_tiles · set_map_tiles · fill_region · apply_autotile · scatter_tiles

apply_autotile paints an autotile and computes seamless edge variants per cell from 8-neighbour connectivity — give it an organic blob (ponds, lakes, forest), a cells list (rivers, curved paths), or a region rect (rectangular floors only). scatter_tiles distributes clutter at a target density with an optional focal gradient. Together these avoid the blocky ponds and corner-clustered detail that make maps look programmer-generated. See MAP-DESIGN.md §5b.

Layers (Map.data z, drawn z0→z1→z2 = editor Layer 1/2/3) are assigned by role: z0 terrain (autotiles), z1 ground clutter (priority 0), z2 overhead (priority > 0 — canopies and roofs the player walks behind).

Tile ids: 0 = empty; 48–383 = autotiles (slot=id/48-1, variant=id%48); ≥384 = regular tiles (col=(id-384)%8, row=(id-384)/8).

Load get_map_design_guide before authoring — create_map also returns its core rules inline. get_map_size_advisory reports screen count, target focal points, recommended scatter density and oversize warnings for an existing map.

validate_assets · validate_connectivity

validate_assets scans every data file for referenced graphic and audio filenames — tilesets, autotiles, panoramas, fogs, battlebacks, character, battler and icon graphics, animations, windowskin, title, gameover, transition, BGM/BGS/ME and map event sprites — and reports any with no file on disk. Broken references are otherwise silent until runtime. Checks the project's Graphics/ and Audio/ first, then the RTP, matching base name regardless of extension.

validate_connectivity builds the world transfer graph and reports maps unreachable from the start map, transfers pointing at a missing map or an out-of-bounds tile, and dead ends.

create_tileset_identification_harness · get_tileset_catalog · save_tileset_catalog · validate_tileset_catalog · render_tileset_atlas · render_map

create_tileset_identification_harness builds an evidence-first review bundle: the source sheet, a labelled copy with burned-in tile IDs, isolated transparent tile images, source rows, autotile sources, engine metadata, a catalog template and an interactive browser page. Reviewed labels, intended uses, object grids, layers and confidence live in a separate catalog, so passability or visual resemblance cannot silently become a semantic claim. See TILESET-CATALOG.md.

render_tileset_atlas renders a tileset to a labelled PNG — scaled with a grid, each tile's id burned in, passability dots (red = blocked, orange = partial) and a legend of the 7 autotile slots.

render_map renders a map's tile layers to a flat top-down PNG preview outside the editor, so you can see what you built. Composites all three layers using the tileset graphic (ids ≥ 384) and its autotiles (ids 48–383, via a cross-verified 48-variant quadrant table). Options: layers, scale, region, drawGrid, drawEvents, passability. Writes to Data/.mcp-preview/map<NNN>.png and returns the path.

Layout preview only — no priority/overhead draw order, no fog, panorama or weather, and autotile animation uses frame 0. Design notes: SCOPING-map-renderer.md.

classify_asset · verify_tileset · register_tileset

Sorting a sheet by canvas dimensions alone silently mis-imports assets authored for other engines, so these detect the true content tile size (edge-periodicity, where a candidate must evenly divide the canvas, biased toward native 32px) and fingerprint the filename: a $/! prefix means a single-object sprite belonging in Characters, not a tileset; A1–A5 means an MV/MZ autotile sheet only when content is not 32px, otherwise it is a battler variant.

verify_tileset writes a grid-overlay preview so scale problems are visible before import. register_tileset adds a guarded Tilesets.rxdata entry with passages/priorities/terrain Tables sized to the sheet, and declines non-native assets unless explicitly forced.

Database — get_database · get_database_entry · update_database_entry

Generic access to every database file, including those without dedicated tools (Classes, States, Enemies, Troops, CommonEvents, Tilesets…). Tileset passability lives in the passages Table: 0 = passable; 1/2/4/8 = down/left/right/up blocked; 15 = impassable; +64 bush; +128 counter.

Scripts — get_scripts · get_script · update_script · create_script · search_scripts

Full RGSS script access with zlib handling. Sources are stored as [magic, name, zlib-deflated code] triples; per-script magic numbers are not meaningful to the editor. create_script inserts above Main by convention. Binary-safe — script data never passes through UTF-8 conversion.

System — get_system · get_variables · set_variable_name · get_switches · set_switch_name · get_game_title · update_game_title · update_starting_position

How it works

.rxdata files are parsed with a vendored, bug-fixed copy of @hyrious/marshal (src/vendor/marshal/) and converted to plain JSON. Ruby objects become { "_class": "RPG::Actor", ... } with instance variables as fields (no leading @).

Why vendored: upstream ≤0.3.3 mis-decodes negative multibyte Marshal integers — −150 decodes as +106. In XP, healing is negative power, so that bug silently converted every healing skill into a damage skill on save. Details in research/REPORT.md.

The RGSS binary classes Table (tile and parameter grids), Color and Tone have dedicated codecs. On save, strings are written as raw byte strings with no Ruby 1.9 encoding ivars, or XP's Ruby 1.8 / RGSS104E refuses to load them. The game title lives in Game.ini, not in System data — unlike MZ.

Round-trips of all 15 template .rxdata files from the RMXP install are byte-identical.

• Automatic backups — before the first write to any file in a session, the original is copied to Data/.mcp-backup/<name>.bak (project root for Game.ini). See the warning at the top: one per file per session.

• Save-revision marker — map and event writes regenerate System.magic_number, mirroring the editor, so existing save files reload the changed map instead of keeping a stale copy.

• Event list invariants — command lists are normalised on save: every command gets code/indent/parameters, and the trailing {code: 0, indent: 0, parameters: []} terminator is guaranteed.

• Verified engine math — skill tools document XP's real damage algorithm, extracted from Game_Battler 3, and the helpers are calibrated to default-database conventions (heals are negative power with int_f 50).

The server surfaces its own guidance, so any MCP client gets the conventions — not just one that can read this repository:

• Server instructions are sent on connect (governance + map-design rules) and injected into context by most clients.

• The guides are exposed as MCP resources (rpgmaker-xp://docs/…): map-design, tileset-catalog, authoring, wisdom.

• get_map_design_guide returns the full guide; create_map returns its core rules inline.

Testing

npm run build
node test/roundtrip.mjs        # Marshal round-trip against real RMXP data
node test/tools.mjs            # end-to-end tool tests on a scratch project
node test/server-smoke.mjs     # MCP stdio handshake + tool calls
node test/render.mjs           # renderer: autotile table + PNG renders
node test/tileset-catalog.mjs  # catalog validation
node test/authoring.mjs        # map authoring primitives
node test/connectivity.mjs     # transfer-graph validation
node test/validate.mjs         # asset reference checking
node test/extract-scripts.mjs  # Scripts.rxdata extraction

The round-trip test loads every .rxdata file from the RMXP install's new-project template, converts to JSON and back, and verifies byte-identical output. Render tests need local RMXP graphics (the Steam RTP install and the library/Valentine90-ABS fixture) and skip rather than fail when those are absent; the autotile-table integrity check always runs.

Documentation

Credits

Forked from k4zuki0539/-rpgmaker-mz-mcp (RPG Maker MZ MCP Server, MIT), then re-authored for RPG Maker XP. The MZ version targets MZ's JSON data; this fork reads and writes XP's Ruby 1.8 Marshal .rxdata directly, and adds skills, scripts, database and render tooling, a byte-verified Marshal codec, map authoring and map rendering. Upstream authorship and the MIT licence are preserved — see LICENSE.

Maintained by SerifeusStudios. Third-party components and their licences are listed in THIRD-PARTY-NOTICES.md.

RPG Maker XP is a product of Enterbrain / Gotcha Gotcha Games. This project is unaffiliated, and bundles no engine assets.

License

MIT — © 2025 k4zuki0539 (original MZ MCP) and © 2026 SerifeusStudios (XP fork). See LICENSE and THIRD-PARTY-NOTICES.md.