LangSchema.Converter.Anthropic (LangSchema v0.7.1)

Converts a LangSchema into a JSON schema compatible with Anthropic's Structured Outputs.

Supported JSON Schema spec

Reference: https://platform.claude.com/docs/en/build-with-claude/structured-outputs

Supported types

string, number, integer, boolean, object, array, null

Supported keywords

• type, description, enum (strings, numbers, bools, nulls), const, default
• properties, required, additionalProperties (must be false)
• items, minItems (only 0 or 1)
• anyOf, allOf (limited — allOf with $ref not supported)
• $ref, $defs, definitions (no external $ref)
• format (date-time, date, time, duration, email, hostname, uri, ipv4, ipv6, uuid)
• pattern (subset of regex — no backreferences, lookahead/lookbehind, \b)

Unsupported keywords

• minimum, maximum, multipleOf
• minLength, maxLength
• minItems beyond 0 or 1, maxItems
• additionalProperties set to anything other than false
• Recursive schemas

Constraints

• additionalProperties: false is mandatory on all objects
• Max 20 strict tools per request
• Max 24 optional parameters total across all strict schemas
• Max 16 parameters using anyOf or type arrays across all strict schemas
• First-request grammar compilation adds 100–300ms; cached 24 hours

LangSchema implementation status