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https://issues.apache.org/jira/browse/CAMEL-23943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18094594#comment-18094594
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Federico Mariani commented on CAMEL-23943:
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An alternative fix strategy worth considering before hardening the loop:
*Option A — harden the hand-rolled loop* (as described above): add
{{maxIterations}}, corrective handling for hallucinated tool names, proper
error propagation.
*Option B — deprecate and remove the tools *producer* role, and the buggy loop
with it.* Historical context: the standalone function-calling client predates
both the agent component and LangChain4j's {{ToolProvider}} API (merged
upstream 2024-09-03, days after the producer was written in CAMEL-21153) — at
the time, a hand-rolled loop was the only way. Today
{{camel-langchain4j-agent}} covers the same use case with LangChain4j's own
{{AiServices}} loop (bounded round trips, hallucinated-tool-name strategy, tool
error handlers — see CAMEL-23928) and reaches the same tag-registered Camel
route tools. The *consumer* role of {{camel-langchain4j-tools}} (registering
routes as tools) would remain untouched — it is the part the agent depends on.
The component is still marked Preview, which lowers the bar for removing the
producer role.
If Option B is preferred, this issue reduces to: deprecate the producer role
(docs + upgrade guide + {{@Deprecated}}), point users at {{langchain4j-agent}},
and later delete {{LangChain4jToolsProducer}}'s tool loop entirely instead of
maintaining a second, less robust copy of what LangChain4j already provides.
_This comment was drafted by Claude Code on behalf of Federico Mariani._
> camel-langchain4j-tools: unbounded tool-calling loop, crash on hallucinated
> tool names, tool errors swallowed
> -------------------------------------------------------------------------------------------------------------
>
> Key: CAMEL-23943
> URL: https://issues.apache.org/jira/browse/CAMEL-23943
> Project: Camel
> Issue Type: Bug
> Components: camel-langchain4j-tools
> Affects Versions: 4.21.0
> Reporter: Federico Mariani
> Priority: Major
> Attachments: LangChain4jToolExecutionErrorPropagationTest.java,
> LangChain4jToolHallucinatedToolNameTest.java,
> LangChain4jToolUnboundedLoopTest.java
>
>
> The tool-calling loop in {{LangChain4jToolsProducer.toolsChat}} has three
> related defects (all with attached failing reproducer tests):
> # *Unbounded loop*: the loop is a {{do/while(true)}} with no iteration cap
> ({{LangChain4jToolsProducer.java:134-165}}). A model that keeps answering
> with tool calls makes the producer loop forever. Reproducer
> {{LangChain4jToolUnboundedLoopTest}} (mock model that always returns a tool
> call) performed *3025 LLM round trips and 3025 tool executions in 15 seconds*
> before the test timed out. LangChain4j itself caps this via
> {{maxToolCallingRoundTrips}} / {{maxSequentialToolsInvocations}}; the
> component reimplements the loop without an equivalent guard.
> # *Hallucinated tool name crashes the exchange*: the tool is resolved with
> {{.filter(...).findFirst().get()}}
> ({{LangChain4jToolsProducer.java:216-217}}); when the LLM hallucinates a tool
> name the exchange dies with {{java.util.NoSuchElementException: No value
> present}} instead of sending a corrective {{ToolExecutionResultMessage}} back
> to the model. Reproducer: {{LangChain4jToolHallucinatedToolNameTest}}.
> # *Tool exceptions swallowed and garbage fed to the LLM*: {{invokeTools}}
> catches route exceptions into {{toolExchange.setException(e)}} (with a
> literal {{// How to handle this exception?}} comment, lines 267-270), then
> sends {{toolExchange.getIn().getBody(String.class)}} (not an error message)
> back to the LLM as the tool result, and {{ExchangeHelper.copyResults}} leaks
> the swallowed exception onto the main exchange. Reproducer:
> {{LangChain4jToolExecutionErrorPropagationTest}}.
> *Suggested fix*: add a {{maxIterations}} endpoint option (behavior change,
> needs an upgrade-guide entry), return a corrective tool-result message for
> unknown tool names, and feed tool failures to the LLM as an explicit error
> string without failing the main exchange.
> Related: CAMEL-23928 (the agent component gained these exact knobs from
> AiServices; this component reimplements the loop manually).
> _This issue was drafted by Claude Code on behalf of Federico Mariani._
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