fix(tool): allow custom default vision model in OpenAIMultiModalTool

[BukJiang]

AgentScope-Java Version

2.0.0-RC2

Description

When openaiImageToText is called without a model parameter, the fallback
was hardcoded to "gpt-4o". Non-OpenAI-compatible backends (e.g. MiniMax
proxies) don't recognize that model name and return HTTP 503, which looks like
a transient outage and is hard to diagnose.

The @ToolParam description also mentioned gpt-4o and gpt-4-vision-preview
explicitly, steering the LLM toward OpenAI-specific names even when a different
backend was configured.

Fixes #1694

Changes:

• Add defaultModelName field and a new 3-argument constructor
  OpenAIMultiModalTool(String apiKey, String baseUrl, String defaultModelName)
• Existing 1-arg and 2-arg constructors delegate to the new one with "gpt-4o"
  as the default (fully backward compatible)
• Replace the hardcoded "gpt-4o" fallback in openaiImageToText with
  this.defaultModelName
• Remove OpenAI-specific model name hints from the @ToolParam description
  and Javadoc

Checklist

• Code has been formatted with mvn spotless:apply
• All tests are passing (mvn test)
• Javadoc comments are complete and follow project conventions
• Related documentation has been updated (e.g. links, examples, etc.)
• Code is ready for review

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ope/core/tool/multimodal/OpenAIMultiModalTool.java	50.00%	6 Missing and 2 partials ⚠️

📢 Thoughts on this report? Let us know!

[AgentScopeJavaBot]

🤖 AI Review

This PR cleanly addresses a real usability issue (#1694) where the hardcoded "gpt-4o" fallback in openaiImageToText causes opaque 503 errors on non-OpenAI-compatible backends. The fix introduces a defaultModelName field with a new 3-arg constructor while keeping existing 1-arg and 2-arg constructors fully backward compatible. Validation is consistent across both public and protected constructors, and the @ToolParam description is appropriately de-coupled from OpenAI-specific model names. Tests cover the custom default model path and constructor validation for null/blank inputs. The change is minimal, well-scoped, and correctly solves the reported issue.

Note: The same hardcoded-default pattern exists in sibling methods (openaiTextToImage → "dall-e-3", openaiTextToAudio → "tts-1", openaiAudioToText → "whisper-1"). These are out of scope for this PR but would benefit from a similar refactoring in a follow-up.

[AgentScopeJavaBot]

🤖 AI Review

This PR cleanly addresses a real usability issue (#1694) where the hardcoded "gpt-4o" fallback in openaiImageToText causes opaque 503 errors on non-OpenAI-compatible backends. The fix introduces a defaultModelName field with a new 3-arg constructor while keeping existing 1-arg and 2-arg constructors fully backward compatible. Validation is consistent across both public and protected constructors, and the @ToolParam description is appropriately de-coupled from OpenAI-specific model names. Tests cover the custom default model path and constructor validation for null/blank inputs. The change is minimal, well-scoped, and correctly solves the reported issue.

Note: The same hardcoded-default pattern exists in sibling methods (openaiTextToImage → "dall-e-3", openaiTextToAudio → "tts-1", openaiAudioToText → "whisper-1"). These are out of scope for this PR but would benefit from a similar refactoring in a follow-up.

[chickenlj]

LGTM.