diff --git a/pkg/server/server.go b/pkg/server/server.go
index a8580df..708b242 100644
--- a/pkg/server/server.go
+++ b/pkg/server/server.go
@@ -826,13 +826,14 @@ func handleToolCallJSONRPC(connID string, req *jsonRPCRequest, toolSet *mcp.Tool
 			log.Printf("Received response body for tool '%s': %s", params.ToolName, string(bodyBytes))
 			// Check status code for API-level errors
 			if httpResp.StatusCode < 200 || httpResp.StatusCode >= 300 {
+				// Put error details into the Content field so MCP clients can access them
+				errText := fmt.Sprintf("Tool '%s' API call failed with status %s: %s", params.ToolName, httpResp.Status, string(bodyBytes))
 				resultPayload = ToolResultPayload{
 					IsError: true,
-					Error: &MCPError{
-						Code:    httpResp.StatusCode,
-						Message: fmt.Sprintf("Tool '%s' API call failed with status %s", params.ToolName, httpResp.Status),
-						Data:    string(bodyBytes), // Include response body in error data
-					},
+					Content: []ToolResultContent{{
+						Type: "text",
+						Text: errText,
+					}},
 					ToolCallID: fmt.Sprintf("%v", req.ID),
 				}
 			} else {
diff --git a/pkg/server/server_test.go b/pkg/server/server_test.go
index 86421b9..3ea4e51 100644
--- a/pkg/server/server_test.go
+++ b/pkg/server/server_test.go
@@ -187,13 +187,13 @@ func TestHttpMethodPostHandler(t *testing.T) {
 			expectedSyncStatus: http.StatusAccepted,
 			expectedSyncBody:   "Request accepted, response will be sent via SSE.\n",
 			checkAsyncResponse: func(t *testing.T, resp jsonRPCResponse) {
-				assert.Equal(t, "call-post-err-1", resp.ID)
-				assert.Nil(t, resp.Error)
-				resultPayload, ok := resp.Result.(ToolResultPayload)
-				require.True(t, ok)
-				assert.True(t, resultPayload.IsError)
-				require.NotNil(t, resultPayload.Error)
-				assert.Contains(t, resultPayload.Error.Message, "operation details for tool 'nonexistent_tool' not found")
+                               assert.Equal(t, "call-post-err-1", resp.ID)
+                               assert.Nil(t, resp.Error)
+                               resultPayload, ok := resp.Result.(ToolResultPayload)
+                               require.True(t, ok)
+                               assert.True(t, resultPayload.IsError)
+                               require.NotNil(t, resultPayload.Error)
+                               assert.Contains(t, resultPayload.Error.Message, "operation details for tool 'nonexistent_tool' not found")
 			},
 		},
 		{