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Defined in: src/genai/tool.ts:43 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.

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Example

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Extends

  • SpanBase

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Properties

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args

readonly args: string
Defined in: src/genai/tool.ts:52

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name

readonly name: string
Defined in: src/genai/tool.ts:51

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result?

optional result?: string
Defined in: src/genai/tool.ts:47 Tool output as a string. Recorded on gen_ai.tool.call.result at end().

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toolCallId

readonly toolCallId: string
Defined in: src/genai/tool.ts:53

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Methods

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addEvent()

Deprecated. Record this data via setAttributes instead. OpenTelemetry is phasing out the Span Event API (Span.addEvent). This method still works and existing span-event data stays valid. See https://opentelemetry.io/blog/2026/deprecating-span-events/
addEvent(name, attributes?, startTime?): this
Defined in: src/genai/spanBase.ts:82 Add a named event to the span. Useful for marking non-span moments such as context compaction, tool-loop detection, or guardrail trips. Warns and no-ops after end(). Mirrors OTel Span.addEvent.

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Parameters

name
string
attributes?
Attributes
startTime?
TimeInput

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Returns

this

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Example

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Inherited from

SpanBase.addEvent

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end()

end(opts?): void
Defined in: src/genai/tool.ts:87 Flush result to the span and close it. Idempotent. Pass error to mark the span as failed; pass endTime to backdate the close.

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Parameters

opts?
SpanEndOptions

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Returns

void

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setAttributes()

setAttributes(attributes): this
Defined in: src/genai/spanBase.ts:63 Set multiple attributes on the span at once. Warns and no-ops after end(). Mirrors OTel Span.setAttributes (and the Python SDK’s set_attributes).

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Parameters

attributes
Attributes

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Returns

this

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Example

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Inherited from

SpanBase.setAttributes