Assistant responds in wrong language

urrlich

In my custom instructions for assistant I have this sentence: "The user speaks English and German, respond in the language the question is asked in." I also say that I live in Germany. The custom instructions are in English. When I ask Assistant what it knows about me I see that it picks up all the information.
When I ask a question in English in Research mode, it often responds in German instead of English. When I ask why it's responding in German it doesn't really answer the question but searches again and repeats the response in English.
Here's an example:
https://kagi.com/assistant/9c8f2e36-c1de-43d2-8019-35f8c9b6adcc
When I ask in German, the response is always in German.
My OS is set to use English, as is the browser.

I would expect the custom instructions to be followed and the response to be in the language of the question.

yiwei-1

urrlich Just to double-check: is your Kagi interface language set to English? Also, have you tried running the query without any custom instructions? If so, does it still respond in German by default?

RoxyRoxyRoxy

CC @yiwei-1

nichu42

Happened to me as well. But also directly on claude.ai, where I use the same prompt.

yiwei-1

nichu42 Do you have any custom instruction set in Claude.ai?

nichu42

yiwei-1 yes, see above. Same as in Kagi:

LANGUAGE PROTOCOL:

Response Language: Always respond in the language of the query. If the query is in German, respond in German. If in English, respond in English.
Mixed-Language Queries: When a query contains both German and English, default to the language in which the primary question is posed.
Explicit Override: If the user explicitly requests a response in a different language (e.g., "Antworte auf Deutsch"), follow that instruction.
Universal Terms: Keep the following in English: product names, code snippets, mathematical notation, standardized technical terms (API, CPU, GDP), and direct quotations from English-language sources.
German-Specific Conventions:
a) Use "Sie" (formal address) unless the user explicitly uses "du."
b) For legal citations, use German designations where applicable (e.g., "Art. 5 GG") but provide an English gloss in parentheses if responding in English.
c) German compound nouns lacking direct English equivalents should be kept in German with a brief English explanation on first use.
Source Language: Use the original title language when citing. If a source exists in both languages (e.g., EU regulations), cite the version matching the response language.

urrlich

Sorry for not replying earlier. I tried using Assistant without custom instructions for a few days and it always responded in the language of the query. Then I added my old custom instruction again, but without the sentence explicitly asking for a response in the query language. Again, always works as intended.
So it looks like it got confused by the language response sentence in my custom instructions, possibly because the sentence duplicated something that's in the built-in custom instructions already (if I understand nichu42 correctly).