Header: 'anthropic-beta': 'interleaved-thinking-2025-05-14' Causes error "...`tool_use` ids were found without `tool_result` blocks immediately after: ..."

[Thimows]

Description

It seems like when using Claude Sonnet 4 with the beta header:

const anthropic = createAnthropic({
headers: {
'anthropic-beta': 'interleaved-thinking-2025-05-14'
}
});

Causes the following issue when you send a follow up message after a message which contains a tool call and the "interleaved-thinking" thinking/reasoning blocks:

7: `tool_use` ids were found without `tool_result` blocks immediately after: toolu_018YfQDEboEehRZvnmFZUrTU. Each `tool_use` block must have a corresponding `tool_result` block in

The is a beta header of course, so I am not sure if this is a AI SDK or Claude error. But it seems like Claude is expecting a certain format which gets disrupted by the interleaved reasoning blocks.

AI SDK Version

"ai": "^4.3.16",
"@ai-sdk/anthropic": "^1.2.12"

[pksorensen]

I got this too, my ai had generated that // 'anthropic-beta': 'interleaved-thinking-2025-05-14', - thanks for pointing that out.

removing that things works as normaly

[sidlak-c137]

You can patch the package like this to make it work:

diff --git a/dist/index.mjs b/dist/index.mjs
index 92a80377692488c4ba8801ce33e7736ad7055e43..fb23cfeebac7b9871cad49bcdb6844d2790ccf12 100644
--- a/dist/index.mjs
+++ b/dist/index.mjs
@@ -1844,6 +1844,9 @@ function convertToCoreMessages(messages, options) {
               }
               case "file":
               case "reasoning": {
+		if (blockHasToolInvocations) {
+                  processBlock2();
+                }
                 block.push(part);
                 break;
               }

Basically, reasoning blocks cant be placed between tool calls and tool results, so we have to do a similar thing to text blocks

[lgrammel]

Can you see if this still happens with ai sdk 5 beta? we are handling blocks differently now

[pheuter]

works for me on the latest beta 👍