Function getToolSearchMode

src/utils/toolSearch.ts:172–198

()

 *   (unset)               tst (default: always defer MCP and shouldDefer tools)
 */
export function getToolSearchMode(): ToolSearchMode {
  // CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS is a kill switch for beta API
  // features. Tool search emits defer_loading on tool definitions and
  // tool_reference content blocks — both require the API to accept a beta
  // header. When the kill switch is set, force 'standard' so no beta shapes
  // reach the wire, even if ENABLE_TOOL_SEARCH is also set. This is the
  // explicit escape hatch for proxy gateways that the heuristic in
  // isToolSearchEnabledOptimistic doesn't cover.
  // github.com/anthropics/claude-code/issues/20031
  if (isEnvTruthy(process.env.CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS)) {
    return 'standard'
  }

  const value = process.env.ENABLE_TOOL_SEARCH

  // Handle auto:N syntax - check edge cases first
  const autoPercent = value ? parseAutoPercentage(value) : null
  if (autoPercent === 0) return 'tst' // auto:0 = always enabled
  if (autoPercent === 100) return 'standard'
  if (isAutoToolSearchMode(value)) {
    return 'tst-auto' // auto or auto:1-99
  }

  if (isEnvTruthy(value)) return 'tst'
  if (isEnvDefinedFalsy(process.env.ENABLE_TOOL_SEARCH)) return 'standard'
  return 'tst' // default: always defer MCP and shouldDefer tools
}

/**
 * Default patterns for models that do NOT support tool_reference.