Tool Versions, GPT-5.4 Models, and SMS Campaign Guardrails

v26.5.28

Published: May 28, 2026

This week's update to the Syllable Agentic Platform adds tool version history with inline comments, a Dynamic Language Switching agent setting, expanded Large Language Model choices with GPT-5.4 and GPT-5.5 while retiring deprecated Gemini 2.0 Flash models, limits SMS campaigns to A2P-verified numbers, improves Insights workflow management, fixes the voice groups list preview, and speeds up the Sessions list.

Agents

• Added Dynamic Language Switching as an Agent setting in create, edit, and details views so callers can switch languages at any point in a conversation by asking naturally.
• Added GPT-5.4, GPT-5.4 mini, GPT-5.4 nano, and GPT-5.5 Large Language Models via OpenAI and Azure OpenAI, and extended Azure OpenAI support to GPT-4.1 mini, GPT-4.1 nano, GPT-5, GPT-5 mini, GPT-5 nano, GPT-5.1, and GPT-5.2, so users can configure agents on the latest OpenAI models.
• Removed Gemini 2.0 Flash and Gemini 2.0 Flash Lite from supported Large Language Model options and updated platform defaults to Gemini 2.5 Flash so agents and tools use supported models before Google's June 2026 deprecation.

Tools

• Enabled version history and inline comments when editing tools so builders can track changes over time and document why a change was made without leaving the editor.

Campaigns

• Limited SMS campaigns to A2P-verified Twilio numbers as the campaign source so launches cannot accidentally use numbers whose messages carriers would block or filter.
• Added batch_id to outbound campaign webhook request bodies so integrators can correlate webhook events with a specific campaign batch.

Insights

• Added duplicate and delete actions to the Workflows table in Insights so users can copy or remove insight workflows directly from the list view.
• Redirected users to the Folder details page after a successful file upload so uploaded files are visible immediately without an extra Close step.

Voices

• Fixed the Voices groups list preview so groups with more than four languages show four language chips plus a +N indicator with a tooltip listing hidden languages, and groups with four or fewer languages show every language without omitting one from the preview.

Sessions

• Improved Sessions list load time by defaulting the table to the last three hours instead of the current moment, so opening Sessions returns results faster when workspaces have large session volumes.