Function checkAutoThreshold

src/utils/toolSearch.ts:712–756

* Check whether deferred tools exceed the auto-threshold for enabling TST. * Tries exact token count first; falls back to character-based heuristic.

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

 * Tries exact token count first; falls back to character-based heuristic.
 */
async function checkAutoThreshold(
  tools: Tools,
  getToolPermissionContext: () => Promise<ToolPermissionContext>,
  agents: AgentDefinition[],
  model: string,
): Promise<{
  enabled: boolean
  debugDescription: string
  metrics: Record<string, number>
}> {
  // Try exact token count first (cached, one API call per toolset change)
  const deferredToolTokens = await getDeferredToolTokenCount(
    tools,
    getToolPermissionContext,
    agents,
    model,
  )

  if (deferredToolTokens !== null) {
    const threshold = getAutoToolSearchTokenThreshold(model)
    return {
      enabled: deferredToolTokens >= threshold,
      debugDescription:
        `${deferredToolTokens} tokens (threshold: ${threshold}, ` +
        `${getAutoToolSearchPercentage()}% of context)`,
      metrics: { deferredToolTokens, threshold },
    }
  }

  // Fallback: character-based heuristic when token API is unavailable
  const deferredToolDescriptionChars =
    await calculateDeferredToolDescriptionChars(
      tools,
      getToolPermissionContext,
      agents,
    )
  const charThreshold = getAutoToolSearchCharThreshold(model)
  return {
    enabled: deferredToolDescriptionChars >= charThreshold,
    debugDescription:
      `${deferredToolDescriptionChars} chars (threshold: ${charThreshold}, ` +
      `${getAutoToolSearchPercentage()}% of context) (char fallback)`,
    metrics: { deferredToolDescriptionChars, charThreshold },
  }
}