Cut OpenAI costs with the Responses API (migration + workflow triage checklist)
Cut OpenAI costs with the Responses API — learn a step-by-step migration path from Assistants API and a workflow triage checklist for Pipedream and Zapier.
If you are still running production workflows on the Assistants API, migrating to the Responses API can reduce operational drag, simplify orchestration, and help you control token spend. The big win is not “a cheaper endpoint.” The win is using the migration as a forcing function to measure what each step costs, split work into cheaper and more expensive stages, and eliminate duplicate runs.
Photo by Michael Dziedzic on Unsplash
The fastest way to cut OpenAI spend (before any migration)
Token costs come from 3 places:
Input tokens (your system prompt, developer instructions, user content, and any retrieved content)
Output tokens (the model’s response)
Extra calls (tool calls, retries, multi-step chains, or “one logical task = 3 API requests”)
Before you change anything, create a baseline so you can prove you reduced cost.
Lightweight measurement plan (30 minutes)
Pick your top 1 to 3 workflows by volume.
For each run, log:
Model name
Input tokens, output tokens, total tokens
Whether tools ran and how many times
Latency
Error or retry count
Summarize after 24 hours:
Total calls
Total tokens
Cost estimate
Top 3 cost drivers (usually “huge transcripts,” “duplicate runs,” or “too many expensive steps”)
If you are orchestrating in an automation platform, do the same for platform-side costs:
In Pipedream, identify the highest task consumption workflows and duplicates.
In Zapier, identify which steps consume tasks and which are free utilities.
Assistants API vs Responses API: what changes in practice
Most teams do not migrate because it is “new.” They migrate because it is becoming the path forward and the new mental model is simpler to reason about.
Here is the practical difference:
Assistants API tends to encourage “one assistant handles everything,” which can hide cost drivers inside threads, runs, and tool calls.
Responses API encourages you to treat each response as an explicit unit of work.
That shift makes it easier to:
Split work into smaller calls
Route simple steps to cheaper models
Keep expensive context out of every request
Migration path: Assistants API → Responses API
Use this order so you do not break production.
Step 1: inventory what your assistants actually do
For each assistant, write down:
The job to be done (one sentence)
The inputs (transcript, CRM fields, ticket text, etc.)
The outputs (JSON fields, summaries, classifications)
Any tools (file search, web search, code, function calls)
Are two versions of the same workflow running in parallel?
Did an “A/B test” accidentally become permanent?
Turning off duplicates is usually the fastest cost win.
2) Reduce input tokens at the source
Do you pass full transcripts when you only need a segment?
Can you send structured metadata instead of raw text?
Can you pre-trim irrelevant sections?
If you are processing voice workflows (for example, call analysis that logs into CRMs like Dialpad), trimming inputs can dwarf all other optimizations.
3) Control output length
Ask for JSON or bullet outputs, not essays.
Use explicit max output constraints.
Avoid “tell me everything” prompts.
4) Route models based on task complexity
Create 2 lanes:
Low-cost lane: high volume, low stakes, structured extraction
If you have 5 prompts that all read the same transcript:
Create one cheap pass that extracts structured facts once.
Feed only those extracted facts into higher-cost reasoning prompts.
This reduces repeated transcript tokens and makes your expensive calls smaller.
Get help migrating your OpenAI workflows
Migrating from the Assistants API to the Responses API usually breaks at the prompt-splitting step — when you realize your modules are still sending the full context window and costs haven't moved. If that's where you're stuck, book a ZoomFlow session — one of our consultants will triage your workflow stack live and identify the highest-impact cost leaks in the same call.
Your monday.com Make API migration checklist: inventory affected scenarios, run a pilot, bulk-update with find/replace, and roll back if anything breaks.