llm_tool_calling_generator 0.6.1

Code generator for llm_tool_calling. Turns @Tool-annotated Dart functions into LLM tools for OpenAI, Gemini and Claude, with JSON schemas and validation.

llm_tool_calling_generator

The code generator for llm_tool_calling: turn any Dart function into an LLM tool with one annotation. No hand-written JSON schemas.

For every @Tool() function it generates a ToolDefinition with the JSON Schema for the LLM, argument validation and type-safe dispatch.

The full documentation, including supported types, validation and errors, and how to send tools to OpenAI, Anthropic or Gemini, is in the llm_tool_calling README.

Quick start

1. Install

dart pub add llm_tool_calling dev:llm_tool_calling_generator dev:build_runner

2. Write a tool

import 'package:llm_tool_calling/llm_tool_calling.dart';

part 'tools.g.dart';

/// Gets the current weather for a city.
@Tool()
String getWeather(
  @Param('City name, e.g. Kanpur') String city, {
  @Param('Use Celsius instead of Fahrenheit') bool celsius = true,
}) => 'Sunny, ${celsius ? '31°C' : '88°F'} in $city';

3. Generate

dart run build_runner build

4. Use the generated getWeatherTool

print(getWeatherTool.parametersSchema); // send to your LLM
print(await getWeatherTool({'city': 'Kanpur'})); // Sunny, 31°C in Kanpur

What gets generated

final getWeatherTool = ToolDefinition(
  name: "getWeather",
  description: "Gets the current weather for a city.",
  parametersSchema: {
    "type": "object",
    "properties": {
      "city": {"type": "string", "description": "City name, e.g. Kanpur"},
      "celsius": {
        "type": "boolean",
        "description": "Use Celsius instead of Fahrenheit",
      },
    },
    "required": ["city"],
    "additionalProperties": false,
  },
  requiresConfirmation: false,
  execute: (args) => getWeather(
    args["city"] as String,
    celsius: args["celsius"] as bool? ?? true,
  ),
);

/// Every tool in this file, e.g. to send to an LLM or look up by name.
final List<ToolDefinition> allTools = [getWeatherTool];

The list is named after the file: tools.dart gives allTools, weather_tools.dart gives weatherTools.

Supported

• Top-level functions: sync, async (Future<T>) and void.

• String, int, double, num, bool, enum, class and List parameters (lists of any of these, including nested lists): positional or named, nullable or not, with or without defaults.

• Descriptions from @Tool(description: ...) or the doc comment.

• Custom JSON names with @Param('...', name: 'game_id'), so your Dart code keeps camelCase while the LLM sees snake case.

• Class parameters become nested object schemas, built through the class's unnamed constructor. freezed classes work too. See Class parameters.

Anything else is a build-time error with a message explaining the fix: unsupported types, missing descriptions, tool names that LLM providers would reject, generic functions, and @Tool on methods.

Troubleshooting

Undefined name 'getWeatherTool': add part 'your_file.g.dart'; and run dart run build_runner build. @Tool only works on top-level functions; in a file with no other top-level annotation, a @Tool method is skipped without a message.

The name 'ToolDefinition' is defined in the libraries ...: another package (e.g. flutter_ai_core) also has a ToolDefinition. Import llm_tool_calling with a prefix (as ltc) and use @ltc.Tool(); the generated code follows your prefix.

Conflicting outputs were detected: run dart run build_runner build --delete-conflicting-outputs.

More in the full troubleshooting guide.

Author

Built and maintained by Amit Gupta. Bug reports, ideas and pull requests are welcome on GitHub. If this package saves you time, a like on pub.dev or a star on GitHub helps others find it.