startTool

▸ startTool(opts): Tool Start a Tool span. Parent resolution (matches the design’s “flat by default, hierarchical if you nest”):

If an LLM is active, the Tool nests under it.
Otherwise, the Tool is a sibling under the current Turn.

Throws if neither a Turn nor an LLM is active.

Parameters

Name	Type
`opts`	`ToolInit`

Returns

Tool Example

weave.startTool({
  name: 'get_weather',
  args: JSON.stringify({city: 'Tokyo'}),
  toolCallId: 'call_t1',
});

Example

weave.startTool({
  name: 'get_weather',
  args: JSON.stringify({city: 'Tokyo'}),
  toolCallId: 'call_t1',
  startTime: new Date('2026-05-29T10:00:00.800Z'),
});

Defined in

src/genai/api.ts:110

startSubagent

startTurn

⌘I

W&B Models

W&B Weave

Serverless Inference

Serverless Training

startTool

startTool

Parameters

Returns

Defined in

​startTool

​Parameters

​Returns

​Defined in

startTool

Parameters

Returns

Defined in