LibreSprite MCP

Instructions

        Run a JavaScript script inside Libresprite.

        IMPORTANT: Make sure you are well versed with the documentation and examples provided in the resources `docs:reference` and `docs:examples`.

        Args:
            script: The script to execute

        Returns:
            Console output
        

Implementation Reference

• src/libresprite_mcp/mcp_server.py:28-42 (handler)

  MCP tool handler for 'run_script', decorated with @self.mcp.tool(), delegates to LibrespriteProxy.

  @self.mcp.tool()
  def run_script(script: str, ctx: Context) -> str:
      """
      Run a JavaScript script inside Libresprite.
  
      IMPORTANT: Make sure you are well versed with the documentation and examples provided in the resources `docs:reference` and `docs:examples`.
  
      Args:
          script: The script to execute
  
      Returns:
          Console output
      """
      return self._libresprite_proxy.run_script(script, ctx)

• src/libresprite_mcp/libresprite_proxy.py:93-124 (handler)

  Core logic of run_script in LibrespriteProxy: sets script on Flask endpoint, waits for output from remote JS, returns console output.

  def run_script(self, script: str, ctx: Context) -> str:
      """
      Run a script in the execution context.
  
      WARNING: This method is synchronous and blocking.
  
      Args:
          script: The script to execute
      """
      # This proxy only allows one script to be executed at a time
      if self._lock:
          ctx.error("Script execution is already in progress...")
          raise RuntimeError("Script execution is already in progress.")
  
      # Sending the script
      ctx.info("Sending script to libresprite...")
      self._lock = True
      self._script = script
      self._script_event.set()
  
      # Waiting for execution
      if not self._output_event.wait(timeout=15):
          ctx.warning("This is taking longer than usual, make sure the user has the Libresprite application with the remote script running?")
      self._output_event.wait()
      self._output_event.clear()
  
      # Return the output
      ctx.info("Script execution completed, checking the logs...")
      output = self._output
      self._output = None
      self._lock = False
      return output

• remote/mcp.js:249-259 (helper)

  Remote JS implementation: executes the received script using new Function, captures output via overridden console.log.

  function runScript(script) {
      if (!script) {
          return;
      }
      try {
          // Execute in global scope with our custom logger...
          new Function('console', script)(console);
      } catch (e) {
          console.log('Error in script:', e.message);
      }
  }

• src/libresprite_mcp/mcp_server.py:28-42 (registration)

  Registration of the 'run_script' tool via FastMCP decorator in _setup_tools method.

  @self.mcp.tool()
  def run_script(script: str, ctx: Context) -> str:
      """
      Run a JavaScript script inside Libresprite.
  
      IMPORTANT: Make sure you are well versed with the documentation and examples provided in the resources `docs:reference` and `docs:examples`.
  
      Args:
          script: The script to execute
  
      Returns:
          Console output
      """
      return self._libresprite_proxy.run_script(script, ctx)