ToolExecutionStartPayload

Payload for “tool_execution_start” events — the host is about to execute a concrete tool request.

This is distinct from “tool_call_start”, which records the model requesting a tool. Tool execution events capture the harness-side action after policy and permission checks.

Class Diagram

---
title: ToolExecutionStartPayload
config:
  look: handDrawn
  theme: colorful
  class:
    hideEmptyMembersBox: true
---
classDiagram
    class ToolExecutionStartPayload {
        +string requestId
        +string toolCallId
        +string toolName
        +dictionary arguments
        +string workingDirectory
        +RedactionMetadata redaction
    }
    class RedactionMetadata {
        +boolean sanitized
        +RedactedField[] fields
        +string policy
    }
    ToolExecutionStartPayload *-- RedactionMetadata

Yaml Example

requestId: exec_abc123
toolCallId: call_abc123
toolName: powershell
workingDirectory: /workspace/project

Properties

Name	Type	Description
requestId	string	Stable host execution request identifier
toolCallId	string	Associated model tool call identifier, when available
toolName	string	Name of the host tool being executed
arguments	dictionary	Tool arguments after host-side sanitization
workingDirectory	string	Working directory or execution scope for the tool
redaction	RedactionMetadata	Redaction state for sensitive argument fields

Composed Types

The following types are composed within ToolExecutionStartPayload:

• RedactionMetadata