The query returns results but the agent says retrieval quality suddenly became terrible — no error appeared. Why?
The silent failure is embedding-space drift. The collection was built with one embedding model and queries are now encoded with another, or preprocessing changed while dimensions stayed compatible. Chroma can perform nearest-neighbor search successfully, but semantic proximity no longer means what you think. The engineering fix is to persist the embedding-model version and preprocessing fingerprint in collection metadata, reject mismatches, and re-index after intentional changes.
How does Chroma MCP compare with a managed vector database?
Chroma offers a simpler, developer-friendly collection model and can run locally or self-hosted; managed vector platforms provide stronger operational guarantees, horizontal scaling, and enterprise controls. Choose Chroma for local RAG and controlled deployments, and a managed service when availability and multi-region operations dominate.
Should the agent write directly to the production collection?
Usually no. Separate ingestion from retrieval, validate chunks, deduplicate by content hash, and quarantine untrusted documents before they can influence answers.
Are similarity scores enough to determine relevance?
No. Scores depend on the embedding model, normalization, corpus, and distance function. Use source-aware evaluation sets and metadata filters, and inspect retrieved passages for actual entailment.