Frequent problems round tripping Assistant messages recieved from anthropic back into create message params.

[bhauman]

I often receive Assistant messages that have an empty .content field marked end turn and when I addMessage to add them to the chat history these messages fail to validate because they have an empty .content list.

I fixed this by removing these messages and not adding them back to the message params.

But not I'm using the websearch tool and I'm receiving WebSearchResultBlock with an empty .content field and these fail to validate as well. The WebSearchResultBlock has an .encrypted_content but not a content.

So basically the pattern of maintaining a chat session is broken.

It seems like message objects are too tightly specified in the JavaSDK and that the json form of these messages and search blocks would be accepted by the api?

This again also happens when an Assistant message has an empty content field.

com.anthropic/anthropic-java {:mvn/version "2.0.0"}

java.lang.IllegalStateException: `content` is required, but was not set
	at com.anthropic.core.Check.checkRequired(Check.kt:12)
	at com.anthropic.models.messages.WebSearchToolResultBlockParam$Builder.build(WebSearchToolResultBlockParam.kt:246)
	at com.anthropic.models.messages.WebSearchToolResultBlock.toParam(WebSearchToolResultBlock.kt:39)
	at com.anthropic.models.messages.ContentBlock$toParam$1.visitWebSearchToolResult(ContentBlock.kt:50)
	at com.anthropic.models.messages.ContentBlock$toParam$1.visitWebSearchToolResult(ContentBlock.kt:36)
	at com.anthropic.models.messages.ContentBlock.accept(ContentBlock.kt:108)
	at com.anthropic.models.messages.ContentBlock.toParam(ContentBlock.kt:35)
	at com.anthropic.models.messages.Message$toParam$1.invoke(Message.kt:55)
	at com.anthropic.models.messages.Message$toParam$1.invoke(Message.kt:55)
	at com.anthropic.core.JsonField.map$anthropic_java_core(Values.kt:197)
	at com.anthropic.models.messages.Message.toParam(Message.kt:55)
	at com.anthropic.models.messages.MessageCreateParams$Body$Builder.addMessage(MessageCreateParams.kt:1808)
	at com.anthropic.models.messages.MessageCreateParams$Builder.addMessage(MessageCreateParams.kt:607)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at clojure.lang.Reflector.invokeMatchingMethod(Reflector.java:196)
	at clojure.lang.Reflector.invokeInstanceMethodOfClass(Reflector.java:106)
	at clojure.lang.Reflector.invokeInstanceMethod(Reflector.java:98)
	at rebel_ai.llm.anthropic$send_message_tool_react_BANG_.invokeStatic(anthropic.clj:275)

And for the Assistant message

Error building MessageCreateParams or sending message
com.anthropic.errors.BadRequestException: 400: {type=error, error={type=invalid_request_error, message=messages.5: all messages must have non-empty content except for the optional final assistant message}}
	at com.anthropic.errors.BadRequestException$Builder.build(BadRequestException.kt:74)
	at com.anthropic.core.handlers.ErrorHandler$withErrorHandler$1.handle(ErrorHandler.kt:45)
	at com.anthropic.services.blocking.MessageServiceImpl$WithRawResponseImpl$createStreaming$1.invoke(MessageServiceImpl.kt:142)
	at com.anthropic.services.blocking.MessageServiceImpl$WithRawResponseImpl$createStreaming$1.invoke(MessageServiceImpl.kt:140)
	at com.anthropic.core.http.HttpResponseForKt$parseable$1$parsed$2.invoke(HttpResponseFor.kt:14)
	at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74)
	at com.anthropic.core.http.HttpResponseForKt$parseable$1.getParsed(HttpResponseFor.kt:14)
	at com.anthropic.core.http.HttpResponseForKt$parseable$1.parse(HttpResponseFor.kt:16)
	at com.anthropic.services.blocking.MessageServiceImpl.createStreaming(MessageServiceImpl.kt:52)
	at com.anthropic.services.blocking.MessageService.createStreaming(MessageService.kt:51)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at clojure.lang.Reflector.invokeMatchingMethod(Reflector.java:196)
	at clojure.lang.Reflector.invokeInstanceMethodOfClass(Reflector.java:106)
	at clojure.lang.Reflector.invokeInstanceMethod(Reflector.java:98)
	at rebel_ai.llm.anthropic$send_session_message.invokeStatic(anthropic.clj:207)

And in both of these cases I'm simply calling addMessage with the response from the MessageAccumulator back into the message params.

[TomerAberbach]

Sorry for the delay here! Thanks for the report.

Can you retry on at least v2.1.0? We improved the robustness of the toParam() methods in that version. I think this should at least fix the IllegalStateException.

The BadRequestException is a bit of a separate issue, which I will need to follow up on.

[michael-cohen-io]

Hey! Would you be able to share a reproducible example where this happened? It would help a ton with root causing this

[michael-cohen-io]

@bhauman would love to get a sense for what is going on here and help but I think I would need some example of when this is occuring

[bhauman]

So there is a very simple reproduction here...

Have Claude create a chat loop with the web-search tool...

Use this
https://github.com/anthropics/anthropic-sdk-java/blob/main/anthropic-java-example/src/main/java/com/anthropic/example/MessagesConversationExample.java
as your template but simply make it read stdin and output to stdout.

If you prompt it to do a websearch then .addMessage with the assistant web-search response message the subsequent request will fail.

Also, I notice with some frequency, that I will receive a response message with no content at all just an empty list.

This also will fail if it you .addMessage the empty response message.