jons-mcp-java

Instructions

Implementation Reference

• src/jons_mcp_java/tools/diagnostics.py:9-43 (handler)

  The main handler for the 'diagnostics' MCP tool, decorated with @mcp.tool(). It retrieves diagnostics from the manager for a specific file or all files and formats them.

  @mcp.tool()
  async def diagnostics(
      file_path: str | None = None,
  ) -> dict:
      """
      Get diagnostics (errors, warnings) for a file or all files.
  
      Args:
          file_path: Optional path to get diagnostics for a specific file.
                    If not provided, returns diagnostics for all files.
  
      Returns:
          Dictionary with 'diagnostics' array containing formatted diagnostic info
      """
      manager = get_manager()
      if manager is None:
          return {"status": "error", "message": "Server not initialized"}
  
      if file_path:
          # Get diagnostics for specific file
          raw_diagnostics = manager.get_diagnostics(Path(file_path))
          formatted = _format_diagnostics(file_path, raw_diagnostics)
          return {"diagnostics": formatted}
      else:
          # Get all diagnostics
          all_raw = manager.get_all_diagnostics()
          all_formatted = []
          for uri, diags in all_raw.items():
              try:
                  path = str(uri_to_path(uri))
              except ValueError:
                  path = uri
              all_formatted.extend(_format_diagnostics(path, diags))
  
          return {"diagnostics": all_formatted}

• src/jons_mcp_java/server.py:64-65 (registration)

  Import of the diagnostics tool (along with others) in the FastMCP server, which registers the tools due to the @mcp.tool() decorators.

  # Import tools to register them
  from jons_mcp_java.tools import navigation, symbols, diagnostics, info  # noqa: E402, F401

• src/jons_mcp_java/tools/diagnostics.py:46-71 (helper)

  Helper function to format raw LSP diagnostics into a standardized dictionary format used by the tool.

  def _format_diagnostics(file_path: str, diagnostics: list) -> list[dict]:
      """Format LSP diagnostics to a user-friendly format."""
      result = []
      for diag in diagnostics:
          range_obj = diag.get("range", {})
          start = range_obj.get("start", {})
  
          severity = diag.get("severity", 1)
          severity_name = {
              1: "error",
              2: "warning",
              3: "information",
              4: "hint",
          }.get(severity, "unknown")
  
          result.append({
              "file": file_path,
              "line": start.get("line", 0),
              "character": start.get("character", 0),
              "severity": severity_name,
              "message": diag.get("message", ""),
              "source": diag.get("source", "jdtls"),
              "code": diag.get("code"),
          })
  
      return result