Opus 5.5 Made Cache Reads 60% Cheaper. I Redid the Math on My Text-to-SQL Architecture

The release of Claude Opus 5.5 has significantly altered the cost-benefit analysis for text-to-SQL applications. With cache reads now 60% cheaper, the price gap between retrieving specific schema subsets and sending the entire schema as a cached prefix has narrowed from 2.1x to 1.2x. For developers like the author of the CRM assistant 'Aria,' this shift suggests that architectural decisions should prioritize accuracy over cost-saving retrieval methods. Furthermore, the migration to Opus 5.5 introduces breaking changes, such as the rejection of forced tool use and stricter requirements for append-only conversations. These updates, combined with the new pricing, encourage a design shift toward static, cached system prompts. The author plans to benchmark these changes by comparing the accuracy and performance of traditional RAG-based schema retrieval against a full-context cached approach to determine the most efficient path forward for SQL generation.