The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →If Codex reports No tool output found for tool call while using DeepSeek, the output may still be in the conversation history. In user-reported failures, a developer or reasoning item sits between a function_call and its matching function_call_output, and DeepSeek’s Responses API rejects the request with HTTP 400. Keeping each call immediately next to its matching output is the reported mitigation; if the same stored history keeps failing, a clean conversation may be needed.
What the error means
The message No tool output found for tool call [call_id] is reported as an HTTP 400 invalid_request_error from DeepSeek’s Responses API. It means the request validator did not accept a usable result paired with the identified call. It does not necessarily mean the serialized history contains no output: reporters say they could see the matching output and call ID, but another item appeared between the call and result. An earlier Codex report describes a similar rejection of cross-provider handoff history even though an output record remained in the rollout. DeepSeek-V3 issue #1588 · DeepSeek API issue #740 · OpenAI Codex issue #38365
As an Amazon Associate I earn from qualifying purchases.
Why item order can matter
The clearest user-supplied reproduction changed the ordering of items sent to POST /v1/responses. With a developer message between a function_call and its matching output, the request returned HTTP 400. With the call immediately followed by the output, it returned HTTP 200; moving the developer message after the output also returned HTTP 200. The reporter also says an interleaved reasoning item triggered the error. These tests used DeepSeek Flash with store: false; they are examples from an issue report, not a guarantee about every model, API version, or configuration. DeepSeek API issue #740
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
This points to a history-ordering compatibility problem rather than proof that the tool itself failed. The reports do not establish adjacency as a formal DeepSeek API contract. DeepSeek’s official Codex integration documentation does not confirm this specific behavior or document a fix.
#1 Best Overall
Why the same Codex session can keep failing
When continuing a conversation, Codex may submit its existing history again. If that history still contains the rejected ordering, the validator can reject the request before the model handles the new user message. Users report repeated failures on continued requests, including a cross-provider handoff where the problematic history remained in the rollout. This is an issue-specific pattern, not evidence that every affected session is permanently unrecoverable. DeepSeek-V3 issue #1588 · OpenAI Codex issue #38365 · DeepSeek API issue #740
How to prevent the ordering problem
Keep the call and result adjacent
In the submitted history, place each function_call immediately before its matching function_call_output. If a hook or harness adds developer context after a tool runs, place that context before the call or after the result instead of between the pair. This is a mitigation reported by users, not an official DeepSeek instruction. DeepSeek-V3 issue #1588 · DeepSeek API issue #740
Normalize history in an adapter you control
If you maintain a provider adapter or history normalizer, match calls and outputs by call_id, then buffer or reorder intervening non-tool items so each pair is adjacent before submission. This broader fix can address multiple sources of interleaving; changing a hook or harness addresses only the source it controls. Reordering also changes transcript sequence, so preserve the intervening context and make the smallest safe adjustment. These trade-offs are practical inferences from the reported reproductions, not vendor-endorsed alternatives. DeepSeek API issue #740
How to recover a session that is already failing
- Capture the evidence first. Record the failing
call_idand the order of request items around its call and output. This helps distinguish an actually missing result from one rejected because of its position; it is practical troubleshooting advice based on the reports. DeepSeek-V3 issue #1588 · DeepSeek API issue #740 - Fix the source of interleaving. Adjust the hook or harness, or normalize the history in the adapter, so the call and its matching output are adjacent on the next request.
- If the same history still fails, start a clean conversation. Carry forward only the user-facing context and work you still need, and preserve relevant material separately before abandoning the old thread. Starting fresh is a reported recovery, not a guarantee for every case. DeepSeek API issue #740
Simply disabling tool definitions is not an established fix for an already malformed history: the reproduction concerns how call and result records are ordered, not whether tools are enabled. DeepSeek API issue #740
Quick Recap
Best Value
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
