schema

func For ¶

func For[T any]() (json.RawMessage, error)

For derives an inline JSON Schema from Go type T. Nested structs are inlined (no $ref/$defs). Descriptions come from the `desc` tag. A field is required unless it is a pointer or its json tag has ",omitempty" or ",omitzero".

It mirrors encoding/json's decoding of T exactly: the object's properties are the fields encoding/json reads, found by the same rules (json tag names, "-" and "-,", embedded structs promoted into the parent unless the tag names them, and Go's dominance rules for fields that embedding supplies more than once, where a tie removes the name altogether). A ",string" field is a JSON string holding the value. []byte is a base64 string but a byte array is an array of numbers; a Go array has exactly its length in items. An integer is bounded by its Go kind (minimum 0 for an unsigned kind, and both bounds for a kind of 32 bits or fewer), and the keys of a map with integer keys are decimal integers (propertyNames). time.Time is a date-time string; json.RawMessage and interface{} are unconstrained. A type that decodes itself is not reflected field by field (reflection cannot see the custom shape), and its DECODING methods decide, as they do for encoding/json: a json.Unmarshaler is unconstrained, and otherwise an encoding.TextUnmarshaler is a string. (A type that only marshals itself is decoded field by field, so it is reflected like any other.) A recursive reference is cut off as an unconstrained object or array.

It returns an error wrapping ErrUnsupportedType for a type encoding/json cannot decode as any schema would describe it: a field reached through an embedded pointer to an unexported struct type, which encoding/json cannot allocate; a json tag name encoding/json does not accept (one with a quote, a backslash, or another reserved character), which encoding/json reads differently depending on how it is built; a kind encoding/json decodes no value but null into (a channel, a function, a complex number, an unsafe.Pointer, an interface with methods, or a map whose key type is not a string, an integer, or an encoding.TextUnmarshaler); and a pointer type that points to itself.

func Gemini ¶ added in v0.7.0

func Gemini(neutral json.RawMessage) (json.RawMessage, error)

Gemini transforms a neutral schema into the OpenAPI 3.0 subset Gemini reads in a function declaration's parameters and in responseSchema:

• A type list with "null" becomes the type plus nullable:true; null in an enum, or a {"type":"null"} branch of anyOf, becomes nullable:true too. A string const becomes a one-value enum.
• additionalProperties:false is dropped (Gemini objects admit only their properties). Validation keywords Gemini lacks (uniqueItems, exclusiveMinimum, exclusiveMaximum, multipleOf), annotations ($schema, $id, $comment, examples, readOnly, writeOnly, deprecated), and a format Gemini does not know for the type are dropped: they only guide the model, and the tool still checks what it receives.
• A construct Gemini cannot express is an error wrapping ErrGeminiUnsupported that names its location: an object with no properties or with additionalProperties (a map, whose keys are data; a recursive type, which For cuts off as an open object), a schema with no type (interface{} or json.RawMessage, which For leaves unconstrained), a list of several non-null types, a non-string enum or const, an array with no items, and any keyword outside the subset ($ref, oneOf, allOf, not, patternProperties, ...).

A tool with no arguments has no schema to send; the Gemini adapter omits its parameters rather than calling this with an empty object, which Gemini rejects.

func OpenAIStrict ¶

func OpenAIStrict(neutral json.RawMessage) (json.RawMessage, error)

OpenAIStrict transforms a neutral schema into OpenAI structured-output "strict" form, which closes every object (additionalProperties:false) and lists every property in required. It changes no set of accepted answers beyond that:

• A property the neutral schema leaves optional (a pointer or omitempty field) stays optional in meaning: it is required but nullable (type [T, "null"], and null added to an enum), so the model sends null rather than inventing a value. encoding/json decodes null into such a field as its zero value.
• An object strict mode cannot close without changing it (a map, whose keys are data; a recursive type, which For cuts off as an open object; any object with no declared properties or with additionalProperties or patternProperties) is an error wrapping ErrStrictUnsupported that names the offending location. Closing it would admit only {}, so every answer would arrive empty.
• An untyped schema ({}, which For gives any and json.RawMessage, or the schema true) admits every value, which strict mode cannot express; it is an error wrapping ErrStrictUnsupported too. So is an array with no items schema (a recursive slice, which For cuts off that way), whose items are untyped.

Operates on the inline schema.