mcp-server-code-runner

Instructions

Implementation Reference

• src/server.ts:22-50 (handler)

  Core handler logic for executing the provided code snippet in the specified language by creating a temporary file and running it with the appropriate executor.

  async ({ code, languageId }) => {
    if (!code) {
      throw new Error("Code is required.");
    }
  
    if (!languageId) {
      throw new Error("Language ID is required.");
    }
  
    const executor = languageIdToExecutorMap[languageId as keyof typeof languageIdToExecutorMap];
  
    if (!executor) {
      throw new Error(`Language '${languageId}' is not supported.`);
    }
  
    const filePath = await createTmpFile(code, languageId);
    const command = `${executor} "${filePath}"`;
  
    const result = await executeCommand(command);
  
    return {
      content: [
        {
          type: "text",
          text: result,
        },
      ],
    };
  },

• src/server.ts:18-21 (schema)

  Zod input schema defining 'code' (string) and 'languageId' (enum from supported languages).

  {
    code: z.string().describe("Code Snippet"),
    languageId: z.enum(Object.keys(languageIdToExecutorMap) as [keyof typeof languageIdToExecutorMap]).describe("Language ID"),
  },

• src/server.ts:15-51 (registration)

  Registration of the 'run-code' tool on the MCP server, including name, description, schema, and handler.

  server.tool(
    "run-code",
    "Run code snippet and return the result.",
    {
      code: z.string().describe("Code Snippet"),
      languageId: z.enum(Object.keys(languageIdToExecutorMap) as [keyof typeof languageIdToExecutorMap]).describe("Language ID"),
    },
    async ({ code, languageId }) => {
      if (!code) {
        throw new Error("Code is required.");
      }
  
      if (!languageId) {
        throw new Error("Language ID is required.");
      }
  
      const executor = languageIdToExecutorMap[languageId as keyof typeof languageIdToExecutorMap];
  
      if (!executor) {
        throw new Error(`Language '${languageId}' is not supported.`);
      }
  
      const filePath = await createTmpFile(code, languageId);
      const command = `${executor} "${filePath}"`;
  
      const result = await executeCommand(command);
  
      return {
        content: [
          {
            type: "text",
            text: result,
          },
        ],
      };
    },
  );

• src/server.ts:74-86 (helper)

  Helper function to execute shell commands and capture stdout, rejecting on error or stderr.

  async function executeCommand(command: string): Promise<string> {
    return new Promise((resolve, reject) => {
      console.debug(`Executing command: ${command}`);
      exec(command, (error: any, stdout: string, stderr: string) => {
        if (error) {
          reject(`Error: ${error.message}`);
        }
        if (stderr) {
          reject(`Stderr: ${stderr}`);
        }
        resolve(stdout);
      });
    });

• src/constants.ts:1-39 (helper)

  Mapping of language IDs to shell executors used by the handler and schema.

  export const languageIdToExecutorMap = {
      javascript: "node",
      php: "php",
      python: "python -u",
      perl: "perl",
      perl6: "perl6",
      ruby: "ruby",
      go: "go run",
      lua: "lua",
      groovy: "groovy",
      powershell: "powershell -ExecutionPolicy ByPass -File",
      bat: "cmd /c",
      shellscript: "bash",
      fsharp: "fsi",
      csharp: "scriptcs",
      vbscript: "cscript //Nologo",
      typescript: "ts-node",
      coffeescript: "coffee",
      scala: "scala",
      swift: "swift",
      julia: "julia",
      crystal: "crystal",
      ocaml: "ocaml",
      r: "Rscript",
      applescript: "osascript",
      clojure: "lein exec",
      racket: "racket",
      scheme: "csi -script",
      ahk: "autohotkey",
      autoit: "autoit3",
      dart: "dart",
      haskell: "runhaskell",
      nim: "nim compile --verbosity:0 --hints:off --run",
      lisp: "sbcl --script",
      kit: "kitc --run",
      v: "v run",
      sass: "sass --style expanded",
      scss: "scss --style expanded",
  };