Class: Tool

TypeScript SDK reference

weave / Tool

A tool invocation. Emits an execute_tool span carrying the tool name, the JSON-encoded arguments, the tool-call id, and the result.

Created by weave.startTool() (or turn.startTool(), or llm.startTool()) and terminated with end(). Assign result before calling end() to record the tool’s output on the span.

Example

const tool = weave.startTool({
  name: tc.function.name,
  args: tc.function.arguments,
  toolCallId: tc.id,
});
try {
  tool.result = await wikipediaSearch(JSON.parse(tc.function.arguments));
} finally {
  tool.end();
}

Table of contents

Properties

• args
• name
• result
• toolCallId

Methods

• end
• create

Properties

args

• Readonly args: string

Defined in

genai/tool.ts:52

---

name

• Readonly name: string

Defined in

genai/tool.ts:51

---

result

• Optional result: string

Tool output as a string. Recorded on gen_ai.tool.call.result at end().

Defined in

genai/tool.ts:45

---

toolCallId

• Readonly toolCallId: string

Defined in

genai/tool.ts:53

Methods

end

▸ end(opts?): void

Flush result to the span and close it. Idempotent. Pass error to mark the span as failed.

Parameters

Name	Type
opts?	Object
opts.error?	Error

Returns

void

Defined in

genai/tool.ts:83

---

create

▸ create(opts): Tool

Parameters

Name	Type
opts	ToolInit & ChildSpanContext

Returns

Tool

Defined in

genai/tool.ts:56