The maxToolInputElements refusal lacks the Input validation error: prefix that the schema refusal carries #3111

Version: @modelcontextprotocol/sdk 1.32.2 (the same text is in packages/server/src/server/mcp.ts on main).

McpServer.validateToolInput refuses a tool call in two ways. Both are McpError(ErrorCode.InvalidParams, …), and the tools/call handler returns either one as an isError: true result:

• arguments over maxToolInputElements:
  Invalid arguments for tool start_run: arguments contain more than the maximum of 50000 elements
• arguments that fail the input schema:
  Input validation error: Invalid arguments for tool get_run_state: Invalid input: expected string, received number at run_id

A client or a log filter that recognises an input refusal by its Input validation error: prefix misses the first one. Yet both are the same kind of refusal: bad arguments, same error code.

Suggestion: give the size refusal the same prefix:
Input validation error: Invalid arguments for tool start_run: arguments contain more than the maximum of 50000 elements

Context: we set maxToolInputElements: 50_000 in Realm's MCP server (thank you for #2926/#2927), and we document both texts for our users.

Related: #2879 asks for a hook to shape the schema refusal's result; if it lands, the size refusal could go through the same hook.