TLDR

Sending tools: [] to OpenAI-compatible APIs causes validation errors like "[] is too short - 'tools'". This happens when no tools are available (e.g., certain model configurations or modes that disable tools). The fix guards all three content generator code paths to only include the tools field when the array is non-empty.

Dive Deeper

Root Cause

Three content generators (OpenAI pipeline, Anthropic generator, logging generator) unconditionally assign the tools field after conversion, even when the result is an empty array:

// Before — sends tools: [] to the API
if (request.config?.tools) {
  baseRequest.tools = await this.converter.convertGeminiToolsToOpenAI(request.config.tools);
}

An empty request.config.tools array is truthy in JavaScript, so the guard passes. The conversion then returns [], which gets sent as tools: [] in the request body. OpenAI's API (and compatible endpoints) rejects this with a validation error.

Fix

Added length checks at both the input and output stages:

// After — only sends tools when non-empty
if (request.config?.tools && request.config.tools.length > 0) {
  const tools = await this.converter.convertGeminiToolsToOpenAI(request.config.tools);
  if (tools.length > 0) {
    baseRequest.tools = tools;
  }
}

The outer check avoids unnecessary conversion of empty input. The inner check handles edge cases where tools have no valid function declarations after conversion.

Files Changed

• packages/core/src/core/openaiContentGenerator/pipeline.ts
• packages/core/src/core/anthropicContentGenerator/anthropicContentGenerator.ts
• packages/core/src/core/loggingContentGenerator/loggingContentGenerator.ts

Reviewer Test Plan

1. npx vitest run packages/core/src/core/openaiContentGenerator/ — 280 tests pass
2. npx vitest run packages/core/src/core/anthropicContentGenerator/ — 44 tests pass

Testing Matrix

Linked issues / bugs

Fixes QwenLM#2054