Rulemorph brings declarative YAML-based data transformation to Claude through four MCP tools: transform for converting CSV, JSON, YAML, TOML, XML, HTML, and Excel into normalized JSON, validate_rules for checking rule syntax, generate_dto for producing TypeScript/Rust/Python/Go/Java/Kotlin/Swift types from your mappings, and analyze_input for summarizing structure. Built on a Rust engine that's also available as a CLI and API server, it uses pipe expressions for field transforms like trim, concat, and numeric ops, plus conditional logic with when clauses and custom reusable definitions. Reach for this when you're wrangling messy external API responses or imports into consistent shapes and want Claude to handle the rule writing and validation instead of maintaining transformation scripts.