---
url: >-
  https://adk.nht.io/api/@nhtio/adk/batteries/llm/litert_lm/helpers/variables/defaultRenderToolsAsPromptText.md
description: 'Default [`renderToolsAsPromptText`](https://adk.nht.io/api/@nhtio/adk/batteries/llm/litert_lm/helpers/functions/renderToolsAsPromptText).'
---

# Variable: defaultRenderToolsAsPromptText

```ts
const defaultRenderToolsAsPromptText: (
  tools: readonly (Tool<SpooledArtifact> | ArtifactTool)[],
  deps: {
    descriptionToChatCompletionsJsonSchema: (d: DescriptionLike) => JsonSchema;
  },
) => string = renderToolsAsPromptText;
```

Defined in: [src/batteries/llm/litert\_lm/helpers.ts:194](https://github.com/NHTIO/ADK/blob/v1.20260713.1/src/src/batteries/llm/litert_lm/helpers.ts#L194)

Default [renderToolsAsPromptText](../functions/renderToolsAsPromptText.md).

Render tool definitions as a SYSTEM-PROMPT text block (the prompt-injection tool-delivery path),
rather than the native `preface.tools` field.

## Parameters

| Parameter                                     | Type                                                                                                                                                                                                                 |
| --------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `tools`                                       | readonly ( | [`Tool`](../../../../../forge/classes/Tool.md)<[`SpooledArtifact`](../../../../../spooled_artifact/classes/SpooledArtifact.md)> | [`ArtifactTool`](../../../../../forge/classes/ArtifactTool.md))\[] |
| `deps`                                        | { `descriptionToChatCompletionsJsonSchema`: (`d`: [`DescriptionLike`](../../../../interfaces/DescriptionLike.md)) => [`JsonSchema`](../../../../interfaces/JsonSchema.md); }                                       |
| `deps.descriptionToChatCompletionsJsonSchema` | (`d`: [`DescriptionLike`](../../../../interfaces/DescriptionLike.md)) => [`JsonSchema`](../../../../interfaces/JsonSchema.md)                                                                                        |

## Returns

`string`

## Remarks

**Why this exists.** LiteRT-LM applies the model's OWN bundled chat template; for the Gemma-4
`.litertlm` preview builds, the template's tools branch is broken — passing `preface.tools` throws
`Failed to apply template: undefined value` inside the wasm runtime (a known Gemma-4 chat-template
bug, also seen in llama.cpp / mlx-lm / LM Studio when `tools[]` hits the native template). The
portable fix every other browser runtime uses (WebLLM/MLC, Open WebUI's "default" mode) is to
describe the tools as TEXT in the system prompt and parse the model's emitted call out of the output
— which the shared [createAutoToolCallParser](../../../transformers_js/helpers/functions/createAutoToolCallParser.md) already does (its `gemma` family handles the
decoder-stripped `call:NAME{…}` runtime form, plus hermes/pythonic as fallbacks).

The block lists each tool's name, description, and JSON-Schema parameters, then instructs Gemma's
OWN trained call format `call:NAME{key:value, …}` — NOT the pythonic `[func(arg=value)]` form. This
matters: the LiteRT-web runtime is Gemma-only, and a real Gemma E2B/E4B run emits the
decoder-stripped `call:NAME{…}` shape natively (verified via the real-model matrix; the `gemma`
family in [createAutoToolCallParser](../../../transformers_js/helpers/functions/createAutoToolCallParser.md) is built for exactly this). Instructing the pythonic form
instead FIGHTS the model's training — a small instruct model, caught between its trained format and a
conflicting instruction, degenerates to an unparseable hybrid (e.g. `say_i_dont_know\nreason: …`)
that no parser catches, so the "call" leaks into the answer as prose. Teaching the model the format
it already knows makes its natural output parse on the first try. A concrete example is included
because a 2B follows a shown example far more reliably than an abstract grammar.