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new 7e10b35aec47 CAMEL-23943: Fix three defects in camel-langchain4j-tools
producer (#24991)
7e10b35aec47 is described below
commit 7e10b35aec477d0eecda8a754f68437af485e45d
Author: Guillaume Nodet <[email protected]>
AuthorDate: Thu Jul 23 11:34:05 2026 +0200
CAMEL-23943: Fix three defects in camel-langchain4j-tools producer (#24991)
CAMEL-23943: Fix three defects in camel-langchain4j-tools producer
1. Unbounded tool-calling loop — added maxToolCallingRoundTrips endpoint
option (default 10)
2. Crash on hallucinated tool names — graceful error message sent back to
the LLM
3. Tool errors swallowed silently — errors now sent back to the LLM as
ToolExecutionResultMessage
Co-authored-by: Claude Opus 4.6 <[email protected]>
---
.../catalog/components/langchain4j-tools.json | 5 +-
.../tools/LangChain4jToolsEndpointConfigurer.java | 6 +
.../tools/LangChain4jToolsEndpointUriFactory.java | 3 +-
.../langchain4j/tools/langchain4j-tools.json | 5 +-
.../tools/LangChain4jToolsEndpoint.java | 26 +++
.../tools/LangChain4jToolsProducer.java | 49 ++++-
.../tools/LangChain4jToolDefectsTest.java | 208 +++++++++++++++++++++
.../ROOT/pages/camel-4x-upgrade-guide-4_22.adoc | 35 ++++
.../LangChain4jToolsEndpointBuilderFactory.java | 38 ++++
9 files changed, 362 insertions(+), 13 deletions(-)
diff --git
a/catalog/camel-catalog/src/generated/resources/org/apache/camel/catalog/components/langchain4j-tools.json
b/catalog/camel-catalog/src/generated/resources/org/apache/camel/catalog/components/langchain4j-tools.json
index 0477acdec1cc..1197e5ae486a 100644
---
a/catalog/camel-catalog/src/generated/resources/org/apache/camel/catalog/components/langchain4j-tools.json
+++
b/catalog/camel-catalog/src/generated/resources/org/apache/camel/catalog/components/langchain4j-tools.json
@@ -47,7 +47,8 @@
"camelToolParameter": { "index": 7, "kind": "parameter", "displayName":
"Camel Tool Parameter", "group": "consumer (advanced)", "label":
"consumer,advanced", "required": false, "type": "object", "javaType":
"org.apache.camel.component.langchain4j.tools.spec.CamelSimpleToolParameter",
"deprecated": false, "deprecationNote": "", "autowired": false, "secret":
false, "description": "Tool's Camel Parameters, programmatically define Tool
description and parameters" },
"exceptionHandler": { "index": 8, "kind": "parameter", "displayName":
"Exception Handler", "group": "consumer (advanced)", "label":
"consumer,advanced", "required": false, "type": "object", "javaType":
"org.apache.camel.spi.ExceptionHandler", "optionalPrefix": "consumer.",
"deprecated": false, "autowired": false, "secret": false, "description": "To
let the consumer use a custom ExceptionHandler. Notice if the option
bridgeErrorHandler is enabled then this option is not in use. By def [...]
"exchangePattern": { "index": 9, "kind": "parameter", "displayName":
"Exchange Pattern", "group": "consumer (advanced)", "label":
"consumer,advanced", "required": false, "type": "enum", "javaType":
"org.apache.camel.ExchangePattern", "enum": [ "InOnly", "InOut" ],
"deprecated": false, "autowired": false, "secret": false, "description": "Sets
the exchange pattern when the consumer creates an exchange." },
- "lazyStartProducer": { "index": 10, "kind": "parameter", "displayName":
"Lazy Start Producer", "group": "producer (advanced)", "label":
"producer,advanced", "required": false, "type": "boolean", "javaType":
"boolean", "deprecated": false, "autowired": false, "secret": false,
"defaultValue": false, "description": "Whether the producer should be started
lazy (on the first message). By starting lazy you can use this to allow
CamelContext and routes to startup in situations where a produ [...]
- "chatModel": { "index": 11, "kind": "parameter", "displayName": "Chat
Model", "group": "advanced", "label": "advanced", "required": false, "type":
"object", "javaType": "dev.langchain4j.model.chat.ChatModel", "deprecated":
false, "deprecationNote": "", "autowired": true, "secret": false,
"configurationClass":
"org.apache.camel.component.langchain4j.tools.LangChain4jToolsConfiguration",
"configurationField": "configuration", "description": "Chat Model of type
dev.langchain4j.model.cha [...]
+ "maxToolCallingRoundTrips": { "index": 10, "kind": "parameter",
"displayName": "Max Tool Calling Round Trips", "group": "producer", "label":
"producer", "required": false, "type": "integer", "javaType": "int",
"deprecated": false, "deprecationNote": "", "autowired": false, "secret":
false, "defaultValue": 10, "description": "Maximum number of tool-calling round
trips (iterations) allowed before stopping. This prevents infinite loops when
the LLM keeps requesting tool calls indefinite [...]
+ "lazyStartProducer": { "index": 11, "kind": "parameter", "displayName":
"Lazy Start Producer", "group": "producer (advanced)", "label":
"producer,advanced", "required": false, "type": "boolean", "javaType":
"boolean", "deprecated": false, "autowired": false, "secret": false,
"defaultValue": false, "description": "Whether the producer should be started
lazy (on the first message). By starting lazy you can use this to allow
CamelContext and routes to startup in situations where a produ [...]
+ "chatModel": { "index": 12, "kind": "parameter", "displayName": "Chat
Model", "group": "advanced", "label": "advanced", "required": false, "type":
"object", "javaType": "dev.langchain4j.model.chat.ChatModel", "deprecated":
false, "deprecationNote": "", "autowired": true, "secret": false,
"configurationClass":
"org.apache.camel.component.langchain4j.tools.LangChain4jToolsConfiguration",
"configurationField": "configuration", "description": "Chat Model of type
dev.langchain4j.model.cha [...]
}
}
diff --git
a/components/camel-ai/camel-langchain4j-tools/src/generated/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpointConfigurer.java
b/components/camel-ai/camel-langchain4j-tools/src/generated/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpointConfigurer.java
index 65185ab644f1..ba46b334ac78 100644
---
a/components/camel-ai/camel-langchain4j-tools/src/generated/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpointConfigurer.java
+++
b/components/camel-ai/camel-langchain4j-tools/src/generated/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpointConfigurer.java
@@ -37,6 +37,8 @@ public class LangChain4jToolsEndpointConfigurer extends
PropertyConfigurerSuppor
case "exposed": target.setExposed(property(camelContext,
boolean.class, value)); return true;
case "lazystartproducer":
case "lazyStartProducer":
target.setLazyStartProducer(property(camelContext, boolean.class, value));
return true;
+ case "maxtoolcallingroundtrips":
+ case "maxToolCallingRoundTrips":
target.setMaxToolCallingRoundTrips(property(camelContext, int.class, value));
return true;
case "name": target.setName(property(camelContext,
java.lang.String.class, value)); return true;
case "parameters": target.setParameters(property(camelContext,
java.util.Map.class, value)); return true;
case "tags": target.setTags(property(camelContext,
java.lang.String.class, value)); return true;
@@ -66,6 +68,8 @@ public class LangChain4jToolsEndpointConfigurer extends
PropertyConfigurerSuppor
case "exposed": return boolean.class;
case "lazystartproducer":
case "lazyStartProducer": return boolean.class;
+ case "maxtoolcallingroundtrips":
+ case "maxToolCallingRoundTrips": return int.class;
case "name": return java.lang.String.class;
case "parameters": return java.util.Map.class;
case "tags": return java.lang.String.class;
@@ -91,6 +95,8 @@ public class LangChain4jToolsEndpointConfigurer extends
PropertyConfigurerSuppor
case "exposed": return target.isExposed();
case "lazystartproducer":
case "lazyStartProducer": return target.isLazyStartProducer();
+ case "maxtoolcallingroundtrips":
+ case "maxToolCallingRoundTrips": return
target.getMaxToolCallingRoundTrips();
case "name": return target.getName();
case "parameters": return target.getParameters();
case "tags": return target.getTags();
diff --git
a/components/camel-ai/camel-langchain4j-tools/src/generated/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpointUriFactory.java
b/components/camel-ai/camel-langchain4j-tools/src/generated/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpointUriFactory.java
index 4438342fbb65..1d09ac4c5a7d 100644
---
a/components/camel-ai/camel-langchain4j-tools/src/generated/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpointUriFactory.java
+++
b/components/camel-ai/camel-langchain4j-tools/src/generated/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpointUriFactory.java
@@ -24,7 +24,7 @@ public class LangChain4jToolsEndpointUriFactory extends
org.apache.camel.support
private static final Set<String> ENDPOINT_IDENTITY_PROPERTY_NAMES;
private static final Map<String, String> MULTI_VALUE_PREFIXES;
static {
- Set<String> props = new HashSet<>(12);
+ Set<String> props = new HashSet<>(13);
props.add("bridgeErrorHandler");
props.add("camelToolParameter");
props.add("chatModel");
@@ -33,6 +33,7 @@ public class LangChain4jToolsEndpointUriFactory extends
org.apache.camel.support
props.add("exchangePattern");
props.add("exposed");
props.add("lazyStartProducer");
+ props.add("maxToolCallingRoundTrips");
props.add("name");
props.add("parameters");
props.add("tags");
diff --git
a/components/camel-ai/camel-langchain4j-tools/src/generated/resources/META-INF/org/apache/camel/component/langchain4j/tools/langchain4j-tools.json
b/components/camel-ai/camel-langchain4j-tools/src/generated/resources/META-INF/org/apache/camel/component/langchain4j/tools/langchain4j-tools.json
index 0477acdec1cc..1197e5ae486a 100644
---
a/components/camel-ai/camel-langchain4j-tools/src/generated/resources/META-INF/org/apache/camel/component/langchain4j/tools/langchain4j-tools.json
+++
b/components/camel-ai/camel-langchain4j-tools/src/generated/resources/META-INF/org/apache/camel/component/langchain4j/tools/langchain4j-tools.json
@@ -47,7 +47,8 @@
"camelToolParameter": { "index": 7, "kind": "parameter", "displayName":
"Camel Tool Parameter", "group": "consumer (advanced)", "label":
"consumer,advanced", "required": false, "type": "object", "javaType":
"org.apache.camel.component.langchain4j.tools.spec.CamelSimpleToolParameter",
"deprecated": false, "deprecationNote": "", "autowired": false, "secret":
false, "description": "Tool's Camel Parameters, programmatically define Tool
description and parameters" },
"exceptionHandler": { "index": 8, "kind": "parameter", "displayName":
"Exception Handler", "group": "consumer (advanced)", "label":
"consumer,advanced", "required": false, "type": "object", "javaType":
"org.apache.camel.spi.ExceptionHandler", "optionalPrefix": "consumer.",
"deprecated": false, "autowired": false, "secret": false, "description": "To
let the consumer use a custom ExceptionHandler. Notice if the option
bridgeErrorHandler is enabled then this option is not in use. By def [...]
"exchangePattern": { "index": 9, "kind": "parameter", "displayName":
"Exchange Pattern", "group": "consumer (advanced)", "label":
"consumer,advanced", "required": false, "type": "enum", "javaType":
"org.apache.camel.ExchangePattern", "enum": [ "InOnly", "InOut" ],
"deprecated": false, "autowired": false, "secret": false, "description": "Sets
the exchange pattern when the consumer creates an exchange." },
- "lazyStartProducer": { "index": 10, "kind": "parameter", "displayName":
"Lazy Start Producer", "group": "producer (advanced)", "label":
"producer,advanced", "required": false, "type": "boolean", "javaType":
"boolean", "deprecated": false, "autowired": false, "secret": false,
"defaultValue": false, "description": "Whether the producer should be started
lazy (on the first message). By starting lazy you can use this to allow
CamelContext and routes to startup in situations where a produ [...]
- "chatModel": { "index": 11, "kind": "parameter", "displayName": "Chat
Model", "group": "advanced", "label": "advanced", "required": false, "type":
"object", "javaType": "dev.langchain4j.model.chat.ChatModel", "deprecated":
false, "deprecationNote": "", "autowired": true, "secret": false,
"configurationClass":
"org.apache.camel.component.langchain4j.tools.LangChain4jToolsConfiguration",
"configurationField": "configuration", "description": "Chat Model of type
dev.langchain4j.model.cha [...]
+ "maxToolCallingRoundTrips": { "index": 10, "kind": "parameter",
"displayName": "Max Tool Calling Round Trips", "group": "producer", "label":
"producer", "required": false, "type": "integer", "javaType": "int",
"deprecated": false, "deprecationNote": "", "autowired": false, "secret":
false, "defaultValue": 10, "description": "Maximum number of tool-calling round
trips (iterations) allowed before stopping. This prevents infinite loops when
the LLM keeps requesting tool calls indefinite [...]
+ "lazyStartProducer": { "index": 11, "kind": "parameter", "displayName":
"Lazy Start Producer", "group": "producer (advanced)", "label":
"producer,advanced", "required": false, "type": "boolean", "javaType":
"boolean", "deprecated": false, "autowired": false, "secret": false,
"defaultValue": false, "description": "Whether the producer should be started
lazy (on the first message). By starting lazy you can use this to allow
CamelContext and routes to startup in situations where a produ [...]
+ "chatModel": { "index": 12, "kind": "parameter", "displayName": "Chat
Model", "group": "advanced", "label": "advanced", "required": false, "type":
"object", "javaType": "dev.langchain4j.model.chat.ChatModel", "deprecated":
false, "deprecationNote": "", "autowired": true, "secret": false,
"configurationClass":
"org.apache.camel.component.langchain4j.tools.LangChain4jToolsConfiguration",
"configurationField": "configuration", "description": "Chat Model of type
dev.langchain4j.model.cha [...]
}
}
diff --git
a/components/camel-ai/camel-langchain4j-tools/src/main/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpoint.java
b/components/camel-ai/camel-langchain4j-tools/src/main/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpoint.java
index 70e4ba176255..3038384089d5 100644
---
a/components/camel-ai/camel-langchain4j-tools/src/main/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpoint.java
+++
b/components/camel-ai/camel-langchain4j-tools/src/main/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsEndpoint.java
@@ -94,6 +94,14 @@ public class LangChain4jToolsEndpoint extends
DefaultEndpoint {
defaultValue = "true")
private boolean exposed = true;
+ @Metadata(label = "producer")
+ @UriParam(description = "Maximum number of tool-calling round trips
(iterations) allowed before stopping."
+ + " This prevents infinite loops when the LLM
keeps requesting tool calls indefinitely."
+ + " Each round trip consists of one LLM call and
the execution of all tools requested in that call."
+ + " Set to 0 for unlimited (not recommended).",
+ defaultValue = "10")
+ private int maxToolCallingRoundTrips = 10;
+
// Track the tool specification created by this endpoint for proper cleanup
private CamelToolSpecification camelToolSpecification;
@@ -278,6 +286,24 @@ public class LangChain4jToolsEndpoint extends
DefaultEndpoint {
this.exposed = exposed;
}
+ /**
+ * Maximum number of tool-calling round trips allowed
+ *
+ * @return the maximum number of round trips
+ */
+ public int getMaxToolCallingRoundTrips() {
+ return maxToolCallingRoundTrips;
+ }
+
+ public void setMaxToolCallingRoundTrips(int maxToolCallingRoundTrips) {
+ if (maxToolCallingRoundTrips < 0) {
+ throw new IllegalArgumentException(
+ "maxToolCallingRoundTrips must be >= 0 (0 means unlimited,
default is 10), got: "
+ + maxToolCallingRoundTrips);
+ }
+ this.maxToolCallingRoundTrips = maxToolCallingRoundTrips;
+ }
+
@Override
protected void doStop() throws Exception {
super.doStop();
diff --git
a/components/camel-ai/camel-langchain4j-tools/src/main/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsProducer.java
b/components/camel-ai/camel-langchain4j-tools/src/main/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsProducer.java
index b921fe4c5370..620998c06019 100644
---
a/components/camel-ai/camel-langchain4j-tools/src/main/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsProducer.java
+++
b/components/camel-ai/camel-langchain4j-tools/src/main/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolsProducer.java
@@ -20,6 +20,7 @@ import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
+import java.util.stream.Collectors;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
@@ -44,6 +45,7 @@ import dev.langchain4j.model.output.TokenUsage;
import org.apache.camel.Exchange;
import org.apache.camel.InvalidPayloadException;
import org.apache.camel.Message;
+import org.apache.camel.RuntimeCamelException;
import org.apache.camel.TypeConverter;
import
org.apache.camel.component.langchain4j.tools.spec.CamelToolExecutorCache;
import
org.apache.camel.component.langchain4j.tools.spec.CamelToolSpecification;
@@ -130,8 +132,16 @@ public class LangChain4jToolsProducer extends
DefaultProducer {
FinishReason lastFinishReason = null;
// First talk to the model to get the tools to be called
+ final int maxRoundTrips = endpoint.getMaxToolCallingRoundTrips();
int i = 0;
do {
+ // Guard against unbounded tool-calling loops
+ if (maxRoundTrips > 0 && i >= maxRoundTrips) {
+ throw new RuntimeCamelException(
+ "Tool-calling loop exceeded maximum round trips (" +
maxRoundTrips + "). "
+ + "Increase the
maxToolCallingRoundTrips option or investigate why the LLM keeps requesting
tools.");
+ }
+
LOG.debug("Starting iteration {}", i);
final ChatResponse chatResponse = chatWithLLM(chatMessages,
toolPair, exchange);
@@ -213,10 +223,27 @@ public class LangChain4jToolsProducer extends
DefaultProducer {
continue;
}
+ // Find the tool specification — handle hallucinated tool names
gracefully
final CamelToolSpecification camelToolSpecification =
toolPair.callableTools().stream()
- .filter(c ->
c.getToolSpecification().name().equals(toolName)).findFirst().get();
+ .filter(c ->
c.getToolSpecification().name().equals(toolName))
+ .findFirst()
+ .orElse(null);
+
+ if (camelToolSpecification == null) {
+ LOG.warn("Tool '{}' requested by LLM not found in registered
tools", toolName);
+ String availableToolNames = toolPair.callableTools().stream()
+ .map(c -> c.getToolSpecification().name())
+ .collect(Collectors.joining(", "));
+ chatMessages.add(new ToolExecutionResultMessage(
+ toolExecutionRequest.id(),
+ toolExecutionRequest.name(),
+ "Error: Tool '" + toolName + "' not found. Available
tools: " + availableToolNames));
+ i++;
+ continue;
+ }
final Exchange toolExchange = ExchangeHelper.createCopy(baseline,
true);
+ String toolResult;
try {
TypeConverter typeConverter =
endpoint.getCamelContext().getTypeConverter();
@@ -261,20 +288,26 @@ public class LangChain4jToolsProducer extends
DefaultProducer {
});
// Execute the consumer route
-
camelToolSpecification.getConsumer().getProcessor().process(toolExchange);
- i++;
+
+ // Check for exception set by the processor (not thrown)
+ if (toolExchange.getException() != null) {
+ throw toolExchange.getException();
+ }
+
+ ExchangeHelper.copyResults(exchange, toolExchange);
+ toolResult = toolExchange.getIn().getBody(String.class);
} catch (Exception e) {
- // How to handle this exception?
- toolExchange.setException(e);
+ LOG.warn("Error executing tool '{}': {}", toolName,
e.getMessage(), e);
+ String errorDetail = e.getMessage() != null ? e.getMessage() :
e.getClass().getName();
+ toolResult = "Error executing tool '" + toolName + "': " +
errorDetail;
}
- ExchangeHelper.copyResults(exchange, toolExchange);
-
chatMessages.add(new ToolExecutionResultMessage(
toolExecutionRequest.id(),
toolExecutionRequest.name(),
- toolExchange.getIn().getBody(String.class)));
+ toolResult));
+ i++;
}
// Clear route stop flag after all tools so it does not leak
diff --git
a/components/camel-ai/camel-langchain4j-tools/src/test/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolDefectsTest.java
b/components/camel-ai/camel-langchain4j-tools/src/test/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolDefectsTest.java
new file mode 100644
index 000000000000..3efec31a7c8f
--- /dev/null
+++
b/components/camel-ai/camel-langchain4j-tools/src/test/java/org/apache/camel/component/langchain4j/tools/LangChain4jToolDefectsTest.java
@@ -0,0 +1,208 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.component.langchain4j.tools;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+
+import dev.langchain4j.data.message.ChatMessage;
+import dev.langchain4j.data.message.SystemMessage;
+import dev.langchain4j.data.message.UserMessage;
+import dev.langchain4j.model.chat.ChatModel;
+import org.apache.camel.CamelContext;
+import org.apache.camel.Exchange;
+import org.apache.camel.RuntimeCamelException;
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.test.infra.openai.mock.OpenAIMock;
+import org.apache.camel.test.junit6.CamelTestSupport;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for the three defects reported in CAMEL-23943:
+ * <ol>
+ * <li>Unbounded tool-calling loop (do/while(true) with no iteration cap)</li>
+ * <li>Crash on hallucinated tool names (.findFirst().get() throws
NoSuchElementException)</li>
+ * <li>Tool errors swallowed silently</li>
+ * </ol>
+ */
+class LangChain4jToolDefectsTest extends CamelTestSupport {
+
+ protected ChatModel chatModel;
+
+ @RegisterExtension
+ static OpenAIMock openAIMock = new OpenAIMock().builder()
+ // Scenario 1: LLM always requests tools — never stops on its own.
+ // Uses a custom response function that returns a tool call on
every request,
+ // simulating an LLM stuck in an infinite tool-calling loop.
+ .when("Infinite tool loop\n")
+ .thenRespondWith((exchange, input) ->
createAlwaysToolCallResponse())
+ .end()
+ // Scenario 2: LLM hallucinates a tool name that doesn't exist
+ .when("Call a tool that does not exist\n")
+ .invokeTool("HallucinatedToolXyz")
+ .withParam("input", "test")
+ .end()
+ // Scenario 3: LLM calls a tool that throws an exception
+ .when("Call the failing tool\n")
+ .invokeTool("FailingTool")
+ .withParam("input", "test")
+ .build();
+
+ /**
+ * Creates a mock OpenAI response that always requests a tool call. Each
invocation returns unique IDs to simulate a
+ * fresh tool call request from the LLM.
+ */
+ private static String createAlwaysToolCallResponse() {
+ return "{\"id\":\"" + UUID.randomUUID() + "\","
+ + "\"choices\":[{\"finish_reason\":\"tool_calls\",\"index\":0,"
+ +
"\"message\":{\"role\":\"assistant\",\"refusal\":null,\"content\":null,"
+ + "\"tool_calls\":[{\"id\":\"" + UUID.randomUUID() +
"\",\"type\":\"function\","
+ + "\"function\":{\"name\":\"RealTool\","
+ + "\"arguments\":\"{\\\"input\\\":\\\"loop\\\"}\"}}]}}],"
+ +
"\"created\":1234567890,\"model\":\"openai-mock\",\"object\":\"chat.completion\"}";
+ }
+
+ @Override
+ protected void setupResources() throws Exception {
+ super.setupResources();
+ chatModel = ToolsHelper.createModel(openAIMock.getBaseUrl());
+ }
+
+ @Override
+ protected CamelContext createCamelContext() throws Exception {
+ CamelContext context = super.createCamelContext();
+ LangChain4jToolsComponent component
+ = context.getComponent(LangChain4jTools.SCHEME,
LangChain4jToolsComponent.class);
+ component.getConfiguration().setChatModel(chatModel);
+ return context;
+ }
+
+ @Override
+ protected RouteBuilder createRouteBuilder() {
+ return new RouteBuilder() {
+ public void configure() {
+ // Producer with low maxToolCallingRoundTrips for testing the
iteration cap
+ from("direct:testMaxRoundTrips")
+
.to("langchain4j-tools:test1?tags=defect-test&maxToolCallingRoundTrips=2");
+
+ // Producer with default settings for hallucinated tool and
error tests
+ from("direct:testHallucinatedTool")
+ .to("langchain4j-tools:test1?tags=defect-test");
+
+ from("direct:testToolError")
+ .to("langchain4j-tools:test1?tags=defect-test");
+
+ // A real tool that succeeds
+ from("langchain4j-tools:test1?tags=defect-test&name=RealTool"
+ + "&description=A real tool that
works¶meter.input=string")
+ .setBody(simple("{\"result\": \"ok\", \"input\":
\"${header.input}\"}"));
+
+ // A tool that always throws an exception
+
from("langchain4j-tools:test1?tags=defect-test&name=FailingTool"
+ + "&description=A tool that always
fails¶meter.input=string")
+ .throwException(new RuntimeException("Tool execution
failed intentionally"));
+ }
+ };
+ }
+
+ /**
+ * CAMEL-23943 defect 1: The do/while(true) loop in toolsChat has no
iteration cap. If the LLM keeps requesting
+ * tools indefinitely, this never terminates.
+ *
+ * This test uses a mock that always returns tool calls (never a final
text response), simulating an LLM stuck in an
+ * infinite loop. Without the fix, this test would hang indefinitely
(caught by the @Timeout annotation). With the
+ * fix, the loop is bounded by maxToolCallingRoundTrips and throws a
RuntimeCamelException.
+ */
+ @Test
+ @Timeout(10) // Safety net: without the fix, the infinite loop would hang
forever
+ void testMaxToolCallingRoundTripsExceeded() {
+ List<ChatMessage> messages = new ArrayList<>();
+ messages.add(new SystemMessage("You are a helpful assistant."));
+ messages.add(new UserMessage("Infinite tool loop\n"));
+
+ Exchange exchange = fluentTemplate.to("direct:testMaxRoundTrips")
+ .withBody(messages).request(Exchange.class);
+
+ assertThat(exchange).isNotNull();
+ assertThat(exchange.getException())
+ .as("Should throw when max round trips exceeded")
+ .isInstanceOf(RuntimeCamelException.class)
+ .hasMessageContaining("maximum round trips (2)");
+ }
+
+ /**
+ * CAMEL-23943 defect 2: When the LLM hallucinates a tool name that
doesn't exist, .findFirst().get() throws
+ * NoSuchElementException, crashing the producer.
+ *
+ * With the fix, the producer sends an error message back to the LLM
listing available tools, and the LLM responds
+ * with a final text answer instead of crashing.
+ */
+ @Test
+ void testHallucinatedToolNameHandledGracefully() {
+ List<ChatMessage> messages = new ArrayList<>();
+ messages.add(new SystemMessage("You are a helpful assistant."));
+ messages.add(new UserMessage("Call a tool that does not exist\n"));
+
+ Exchange exchange = fluentTemplate.to("direct:testHallucinatedTool")
+ .withBody(messages).request(Exchange.class);
+
+ assertThat(exchange).isNotNull();
+ // Should NOT have an exception — the error is sent back to the LLM
gracefully
+ assertThat(exchange.getException())
+ .as("Hallucinated tool should not crash the producer")
+ .isNull();
+ // The LLM should have responded with a final text answer
+ String body = exchange.getMessage().getBody(String.class);
+ assertThat(body)
+ .as("LLM should return a text response after receiving the
tool error")
+ .isNotNull();
+ }
+
+ /**
+ * CAMEL-23943 defect 3: When a tool route throws an exception, the catch
block sets toolExchange.setException(e)
+ * but the error is swallowed — it's never propagated back to the LLM and
subsequent logic overwrites the exchange
+ * state.
+ *
+ * With the fix, the error is sent back to the LLM as a
ToolExecutionResultMessage, allowing the LLM to handle it
+ * gracefully.
+ */
+ @Test
+ void testToolExecutionErrorPropagatedToLLM() {
+ List<ChatMessage> messages = new ArrayList<>();
+ messages.add(new SystemMessage("You are a helpful assistant."));
+ messages.add(new UserMessage("Call the failing tool\n"));
+
+ Exchange exchange = fluentTemplate.to("direct:testToolError")
+ .withBody(messages).request(Exchange.class);
+
+ assertThat(exchange).isNotNull();
+ // Should NOT have an exception — the tool error is sent back to the
LLM gracefully
+ assertThat(exchange.getException())
+ .as("Tool error should not crash the producer — it should be
sent to the LLM")
+ .isNull();
+ // The LLM should have responded with a final text answer after
receiving the error
+ String body = exchange.getMessage().getBody(String.class);
+ assertThat(body)
+ .as("LLM should return a text response after receiving the
tool error")
+ .isNotNull();
+ }
+}
diff --git
a/docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_22.adoc
b/docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_22.adoc
index bc5d20fdbd83..1a8ceba558ae 100644
--- a/docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_22.adoc
+++ b/docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_22.adoc
@@ -247,6 +247,41 @@ They were not wired into the component; the `chatModel` is
autowired instead.
If you used these helpers directly, configure your `ChatModel` with
LangChain4j's own builders or Spring Boot starters
and inject it into the component.
+=== camel-langchain4j-tools
+
+==== Tool-calling round trips now bounded by default
+
+The `langchain4j-tools` producer now limits the number of tool-calling round
trips to 10 by default
+(previously the loop was unbounded and could run indefinitely if the LLM kept
requesting tools).
+Each round trip consists of one LLM call and the execution of all tools
requested in that call.
+
+If your LLM interaction legitimately requires more than 10 iterations,
increase the
+`maxToolCallingRoundTrips` endpoint option. Set to `0` for unlimited (not
recommended).
+Negative values are rejected with `IllegalArgumentException`.
+
+When the limit is reached, the producer throws a `RuntimeCamelException` with
a message indicating
+the maximum was exceeded.
+
+==== Hallucinated tool names no longer crash the producer
+
+When the LLM requests a tool name that does not exist among the registered
tools, the producer
+now sends an error message back to the LLM listing the available tools, giving
it a chance to
+self-correct. Previously this caused a `NoSuchElementException` crash.
+
+==== Tool execution errors sent to LLM instead of propagating to the route
+
+When a tool route throws an exception, the error is now sent back to the LLM
as a
+`ToolExecutionResultMessage`, allowing the LLM to handle it gracefully (e.g.,
retry with different
+parameters or answer directly). Previously the exception was set on the tool
exchange and
+`ExchangeHelper.copyResults` propagated it onto the main exchange, but the
loop continued anyway,
+leaving the exchange in an inconsistent state.
+
+This is a behavior change: routes that used `onException(...)` to catch tool
execution failures
+will no longer see those exceptions, since the error is now handled within the
producer and sent
+back to the LLM. The previous behavior was unreliable — a later successful
tool call would
+overwrite the exception via `copyResults` — but if you relied on it, be aware
that tool errors
+are now consumed by the producer.
+
=== camel-langchain4j-web-search
The `safeSearch` endpoint option is now correctly propagated to the
LangChain4j `WebSearchRequest`.
diff --git
a/dsl/camel-endpointdsl/src/generated/java/org/apache/camel/builder/endpoint/dsl/LangChain4jToolsEndpointBuilderFactory.java
b/dsl/camel-endpointdsl/src/generated/java/org/apache/camel/builder/endpoint/dsl/LangChain4jToolsEndpointBuilderFactory.java
index f53dd7e54b32..84c3900047f5 100644
---
a/dsl/camel-endpointdsl/src/generated/java/org/apache/camel/builder/endpoint/dsl/LangChain4jToolsEndpointBuilderFactory.java
+++
b/dsl/camel-endpointdsl/src/generated/java/org/apache/camel/builder/endpoint/dsl/LangChain4jToolsEndpointBuilderFactory.java
@@ -386,6 +386,44 @@ public interface LangChain4jToolsEndpointBuilderFactory {
doSetProperty("tags", tags);
return this;
}
+ /**
+ * Maximum number of tool-calling round trips (iterations) allowed
+ * before stopping. This prevents infinite loops when the LLM keeps
+ * requesting tool calls indefinitely. Each round trip consists of one
+ * LLM call and the execution of all tools requested in that call. Set
+ * to 0 for unlimited (not recommended).
+ *
+ * The option is a: <code>int</code> type.
+ *
+ * Default: 10
+ * Group: producer
+ *
+ * @param maxToolCallingRoundTrips the value to set
+ * @return the dsl builder
+ */
+ default LangChain4jToolsEndpointProducerBuilder
maxToolCallingRoundTrips(int maxToolCallingRoundTrips) {
+ doSetProperty("maxToolCallingRoundTrips",
maxToolCallingRoundTrips);
+ return this;
+ }
+ /**
+ * Maximum number of tool-calling round trips (iterations) allowed
+ * before stopping. This prevents infinite loops when the LLM keeps
+ * requesting tool calls indefinitely. Each round trip consists of one
+ * LLM call and the execution of all tools requested in that call. Set
+ * to 0 for unlimited (not recommended).
+ *
+ * The option will be converted to a <code>int</code> type.
+ *
+ * Default: 10
+ * Group: producer
+ *
+ * @param maxToolCallingRoundTrips the value to set
+ * @return the dsl builder
+ */
+ default LangChain4jToolsEndpointProducerBuilder
maxToolCallingRoundTrips(String maxToolCallingRoundTrips) {
+ doSetProperty("maxToolCallingRoundTrips",
maxToolCallingRoundTrips);
+ return this;
+ }
}
/**
