Function isToolSearchEnabled

src/utils/toolSearch.ts:385–473

(
  model: string,
  tools: Tools,
  getToolPermissionContext: () => Promise<ToolPermissionContext>,
  agents: AgentDefinition[],
  source?: string,
)

 * @returns true if tool search should be enabled for this request
 */
export async function isToolSearchEnabled(
  model: string,
  tools: Tools,
  getToolPermissionContext: () => Promise<ToolPermissionContext>,
  agents: AgentDefinition[],
  source?: string,
): Promise<boolean> {
  const mcpToolCount = count(tools, t => t.isMcp)

  // Helper to log the mode decision event
  function logModeDecision(
    enabled: boolean,
    mode: ToolSearchMode,
    reason: string,
    extraProps?: Record<string, number>,
  ): void {
    logEvent('tengu_tool_search_mode_decision', {
      enabled,
      mode: mode as AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
      reason:
        reason as AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
      // Log the actual model being checked, not the session's main model.
      // This is important for debugging subagent tool search decisions where
      // the subagent model (e.g., haiku) differs from the session model (e.g., opus).
      checkedModel:
        model as AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
      mcpToolCount,
      userType: (process.env.USER_TYPE ??
        'external') as AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
      ...extraProps,
    })
  }

  // Check if model supports tool_reference
  if (!modelSupportsToolReference(model)) {
    logForDebugging(
      `Tool search disabled for model '${model}': model does not support tool_reference blocks. ` +
        `This feature is only available on Claude Sonnet 4+, Opus 4+, and newer models.`,
    )
    logModeDecision(false, 'standard', 'model_unsupported')
    return false
  }

  // Check if ToolSearchTool is available (respects disallowedTools)
  if (!isToolSearchToolAvailable(tools)) {
    logForDebugging(
      `Tool search disabled: ToolSearchTool is not available (may have been disallowed via disallowedTools).`,
    )
    logModeDecision(false, 'standard', 'mcp_search_unavailable')
    return false
  }

  const mode = getToolSearchMode()

  switch (mode) {
    case 'tst':
      logModeDecision(true, mode, 'tst_enabled')
      return true