diff --git a/mcp/common/src/main/java/org/springframework/ai/mcp/AsyncMcpToolCallback.java b/mcp/common/src/main/java/org/springframework/ai/mcp/AsyncMcpToolCallback.java
index 95d1b9039..f67b61632 100644
--- a/mcp/common/src/main/java/org/springframework/ai/mcp/AsyncMcpToolCallback.java
+++ b/mcp/common/src/main/java/org/springframework/ai/mcp/AsyncMcpToolCallback.java
@@ -109,9 +109,12 @@ public class AsyncMcpToolCallback implements ToolCallback {
 		Map<String, Object> arguments = ModelOptionsUtils.jsonToMap(functionInput);
 		// Note that we use the original tool name here, not the adapted one from
 		// getToolDefinition
-		return this.asyncMcpClient.callTool(new CallToolRequest(this.tool.name(), arguments))
-			.map(response -> ModelOptionsUtils.toJsonString(response.content()))
-			.block();
+		return this.asyncMcpClient.callTool(new CallToolRequest(this.tool.name(), arguments)).map(response -> {
+			if (response.isError() != null && response.isError()) {
+				throw new IllegalStateException("Error calling tool: " + response.content());
+			}
+			return ModelOptionsUtils.toJsonString(response.content());
+		}).block();
 	}
 
 	@Override
diff --git a/mcp/common/src/main/java/org/springframework/ai/mcp/SyncMcpToolCallback.java b/mcp/common/src/main/java/org/springframework/ai/mcp/SyncMcpToolCallback.java
index 1b71e9301..aa51e1f36 100644
--- a/mcp/common/src/main/java/org/springframework/ai/mcp/SyncMcpToolCallback.java
+++ b/mcp/common/src/main/java/org/springframework/ai/mcp/SyncMcpToolCallback.java
@@ -113,7 +113,7 @@ public class SyncMcpToolCallback implements ToolCallback {
 		// Note that we use the original tool name here, not the adapted one from
 		// getToolDefinition
 		CallToolResult response = this.mcpClient.callTool(new CallToolRequest(this.tool.name(), arguments));
-		if (response.isError()) {
+		if (response.isError() != null && response.isError()) {
 			throw new IllegalStateException("Error calling tool: " + response.content());
 		}
 		return ModelOptionsUtils.toJsonString(response.content());