# `LangChain.Utils.GoogleSchema`
[🔗](https://github.com/brainlid/langchain/blob/v0.13.0/lib/utils/google_schema.ex#L1)

Removes JSON Schema keywords that Google's Gemini APIs reject.

Google's function declarations and response schemas accept a
[select subset](https://ai.google.dev/api/caching#Schema) of an OpenAPI 3.0
schema object rather than full JSON Schema. The `Schema` type is a protobuf
message, so a keyword it has no field for is rejected by the parser before
any semantic validation runs:

    Invalid JSON payload received. Unknown name "additionalProperties" at
    'tools[0].function_declarations[0].parameters': Cannot find field.

That fails the entire request, not the single tool, and the message names a
field path rather than the tool, so the cause is not obvious.

`additionalProperties` is the keyword that matters most in practice, because
`LangChain.FunctionParam.to_parameters_schema/1` adds it to every schema it
generates. Without this sanitizing step, any tool declared the ordinary way —
with a `parameters:` list of `LangChain.FunctionParam` structs — is rejected
by Gemini.

## Semantic loss

One removal changes what the API enforces. Dropping `additionalProperties:
false` means Gemini does not reject unexpected properties, so a tool call's
arguments may contain fields the schema did not declare. Where that matters,
validate the arguments inside the tool's own function.

Schemas built around `$ref` are also flattened, since neither `$ref` nor
`$defs` has a Google equivalent. Inline such schemas before sending them.

# `empty_object?`
[🔗](https://github.com/brainlid/langchain/blob/v0.13.0/lib/utils/google_schema.ex#L116)

```elixir
@spec empty_object?(any()) :: boolean()
```

Return true when the schema describes an object with no properties.

Google rejects such a schema with "should be non-empty for OBJECT type", so a
function declaration that produces one has to omit its parameters entirely
rather than send an empty object.

## Example

    iex> LangChain.Utils.GoogleSchema.empty_object?(%{"type" => "object", "properties" => %{}})
    true

    iex> LangChain.Utils.GoogleSchema.empty_object?(%{"type" => "object", "properties" => %{"a" => %{}}})
    false

# `sanitize`
[🔗](https://github.com/brainlid/langchain/blob/v0.13.0/lib/utils/google_schema.ex#L74)

```elixir
@spec sanitize(map()) :: map()
```

```elixir
@spec sanitize(any()) :: any()
```

Remove the schema keywords Google does not support, recursing through nested
schemas.

Non-map input is returned unchanged, so this is safe to apply to a `nil`
response schema or a schema fragment that is a bare boolean.

## Example

    iex> LangChain.Utils.GoogleSchema.sanitize(%{
    ...>   "type" => "object",
    ...>   "additionalProperties" => false,
    ...>   "properties" => %{"city" => %{"type" => "string"}}
    ...> })
    %{"type" => "object", "properties" => %{"city" => %{"type" => "string"}}}

---

*Consult [api-reference.md](api-reference.md) for complete listing*