Resource/Prompt method callbacks should use INTERNAL_ERROR (-32603) instead of INVALID_PARAMS (-32602) for runtime exceptions

[feelform]

Problem

When a @McpResource or @McpPrompt annotated method throws a runtime exception (e.g., IOException, NullPointerException),
the framework wraps it with ErrorCodes.INVALID_PARAMS (-32602).

However, the MCP specification defines distinct error codes for different failure scenarios:

• -32602 (INVALID_PARAMS): Invalid method parameter(s)
• -32603 (INTERNAL_ERROR): Internal JSON-RPC error

A runtime exception during method execution is an internal error, not an invalid parameter error.

Affected files

All four resource callbacks and all four prompt callbacks use INVALID_PARAMS in the catch block:

Resource:

• SyncMcpResourceMethodCallback.java:129
• AsyncMcpResourceMethodCallback.java:143
• SyncStatelessMcpResourceMethodCallback.java:124
• AsyncStatelessMcpResourceMethodCallback.java:137

Prompt:

• SyncMcpPromptMethodCallback.java:114
• AsyncMcpPromptMethodCallback.java:122
• SyncStatelessMcpPromptMethodCallback.java:108
• AsyncStatelessMcpPromptMethodCallback.java:119

Example (SyncMcpResourceMethodCallback.java:124-135)

catch (Exception e) {
if (e instanceof McpError mcpError && mcpError.getJsonRpcError() != null) {
throw mcpError;
}

  throw McpError.builder(ErrorCodes.INVALID_PARAMS)  // ← should be ErrorCodes.INTERNAL_ERROR                         
      .message("Error invoking resource method: " + this.method.getName() + " in "                                      
              + this.bean.getClass().getName() + ". /nCause: "
              + ErrorUtils.findCauseUsingPlainJava(e).getMessage())                                                     
      .data(ErrorUtils.findCauseUsingPlainJava(e).getMessage())                                                         
      .build();               

}

Expected behavior

Runtime exceptions during method execution should be wrapped with ErrorCodes.INTERNAL_ERROR (-32603), matching the MCP
specification:

• https://modelcontextprotocol.io/specification/draft/server/resources#error-handling

Additional note

The MCP SDK itself already follows this convention — McpStreamableServerSession uses INTERNAL_ERROR as the fallback when a
handler throws a non-McpError exception (line 184).

Environment

• mcp-annotations: 0.8.0
• mcp-core (SDK): 0.17.0
• Spring AI: 1.1.4