Swap AI Tools Mid-Conversation Without Resetting Context
Update available tools mid-chat without losing your prompt cache or context.
Use the mid-conversation tool change beta header to dynamically swap or add tools during a multi-turn chat session while keeping context intact.
The Scenario
You are running a long multi-turn session with an AI agent. Midway through, you realize the agent needs a specific 'calculator' tool it didn't have initially, but you don't want to lose the current conversation state.
Before & after
To change tools in a conversation, you would have to start a new session or re-send the entire history, consuming thousands of tokens and taking 5–10 minutes of manual context re-management.
By using the 'mid-conversation-tool-changes' beta header, you can add or remove functional tools in 1–2 minutes without wasting tokens or re-uploading the entire prompt history.
The Prompt
// Include the beta header to modify tools mid-stream while keeping your cache
// Extra Headers: { "beta": "mid-conversation-tool-changes-2026-07-01" }
{
"model": "claude-opus-5",
"tools": [[NEW_LIST_OF_TOOLS]],
"messages": [[EXISTING_CONVERSATION_HISTORY]]
}This feature is available on Claude Fable 5, Mythos 5, Opus 4.8, and Opus 5. It allows for dynamic tool adjustment while preserving the prompt cache, saving both money and processing time.
Source
Claude Platform release notes - Claude Platform Docs"add or remove tools between turns of a conversation while preserving the prompt cache. Include the mid-conversation-tool-changes-2026-07-01 beta header."