Defold MCP server

_Defold_MCP.md

Steps to try it out:

1. Add mcp.editor_script to a Defold project
2. Project -> Reload Editor Scripts
3. It will print something like MCP running on http://localhost:50489/mcp — your port will be different
4. Ensure that npx mcp-remote http://localhost:50489/mcp --transport http-only successfully runs in your terminal.
5. Edit Claude desktop config to refer to the server (see claude_desktop_config.json for reference)
6. Restart Claude and enjoy!

claude_desktop_config.json

{
    "mcpServers": {
        "defold": {
            "command": "npx",
            "args": ["mcp-remote", "http://localhost:50489/mcp", "--transport", "http-only"]
        }
    }
}

mcp.editor_script

local M = {}

print(("MCP running on %s/mcp"):format(http.server.local_url))

function M.get_http_server_routes()
    return {
        http.server.route("/mcp", "POST", "json", function(request)
            local method = request.body.method
            if method == "initialize" then
                return http.server.json_response({
                    jsonrpc = "2.0",
                    id = request.body.id,
                    result = {
                        protocolVersion = "2024-11-05",
                        serverInfo = {
                            name = ("Defold (%s)"):format(editor.get("/game.project", "project.title")),
                            version = editor.version or "dev"
                        },
                        capabilities = {
                            logging = {},
                            prompts = {listChanged = true},
                            resources = {
                                subscribe = true,
                                listChanged = true
                            },
                            tools = {listChanged = true}
                        }
                    }
                })
            elseif method == "tools/list" then
                return http.server.json_response({
                    jsonrpc = "2.0",
                    id = request.body.id,
                    result = {tools = {
                        {
                            name = "eval_editor_script",
                            title = "Eval editor script",
                            description = "Eval lua code as editor script. Documentation: https://defold.com/ref/stable/editor-lua/ Some examples: `editor.get('/', 'children')`, `editor.get('/game.project', 'bootstrap.main_collection')`, `return editor.get('/logic.lua', 'text')`",
                            inputSchema = {
                                type = "object",
                                properties = {lua_code = {type = "string"}},
                                required = {"lua_code"}
                            }
                        }
                    }}
                })
            elseif method == "tools/call" then
                local tool_name = request.body.params.name
                if tool_name == "eval_editor_script" then
                    local code = request.body.params.arguments.lua_code
                    local content = {}
                    local print_fn = function(...)
                        local s = ""
                        for i = 1, select("#", ...) do
                            if i ~= 1 then
                                s = s .. " "
                            end
                            s = s .. tostring(select(i, ...))
                        end
                        content[#content+1] = {type = "text", text = s}
                    end
                    local env = {}
                    for key, value in pairs(_G) do
                        env[key] = value
                    end
                    env.print = print_fn
                    local f, err = load(code, "eval", "t", env)
                    local success, result
                    if f then
                        success, result = pcall(f)
                    else
                        success, result = false, err
                    end
                    content[#content+1] = {type = "text", text = tostring(result)}
                    return http.server.json_response({
                        jsonrpc = "2.0",
                        id = request.body.id,
                        result = {
                            isError = not success,
                            content = content
                        }
                    })
                end
            elseif method == "resources/list" then
                return http.server.json_response({
                    jsonrpc = "2.0",
                    id = request.body.id,
                    result = {}
                })
            elseif method == "prompts/list" then
                return http.server.json_response({
                    jsonrpc = "2.0",
                    id = request.body.id,
                    result = {}
                })
            elseif method == "notifications/initialized" then
                return http.server.response()
            else
                pprint(request)
            end
        end)
    }
end

return M