What Is an AI Response Schema Version? (2026): The Contract's Name, Not the Lock

An AI response schema version is the name you give a response shape, such as decision.v3, plus the list of fields that version requires. Callers match on the name. They do not guess from a sample. The version does not force the model to comply. Forcing a failure when the shape is wrong is what an AI output schema lock is. Checking a tool’s return, which is a different payload, is what an AI tool result schema is.

Rejecting a payload that fails the checks you wrote is what AI output validation is. This page is the name and the field list. It is not the validator.

Claude’s prices are from claude.com/pricing on October 24, 2026. ChatGPT’s Plus price is from learn.chatgpt.com/docs/pricing that day. Cursor and GitHub Copilot prices are from directory pages checked October 16, 2026. Published October 24, 2026. We did not score how often a model matches a shape. The directory does not list a schema-version fee.

What a version has to carry

Field	Who writes it	A missing value becomes
The version name	You	The consumer cannot tell v2 from v3
Required fields, and which older fields you removed	You	A silent drop that breaks a caller
The date the version became the one production may emit	You	“Current” with no date
The consumer that is allowed to read it	You	Every caller, including ones you forgot

flowchart TD
  shape["You name the version and list the required fields"] --> emit["A model drafts a payload"]
  emit --> match{"Does the payload carry that version name and those fields?"}
  match -->|No| fail["Validation fails. Do not relabel the payload as the new version"]
  match -->|Yes| caller["The consumer that you listed reads it"]

A model that adds a field and calls the result v4 has not shipped a version. You ship a version when you write the name, the field list, and the date. Two payloads with the same name and different fields are a bug, not a minor update.

Where the name lives

The contract text. Claude Pro is $17 a month billed annually, $200 up front, or $20 monthly. Keep the field list in a Project. A chat that “improves” the JSON is not a release. The review is Claude review.

The code that checks the name. Cursor Plus is $8 a month, or $80 a year. You review the diff. The ladder is Cursor pricing explained.

One example payload. ChatGPT Plus is $20 a month. Paste the field list. Discard an example that adds a field you did not list. The ladder is ChatGPT pricing explained.

The company coding seat. GitHub Copilot Business is $19 a user a month on the October 16 card. The schema check is still your test. The invoice is GitHub Copilot Business pricing explained.

A prompt that holds the line:

“Write an example payload for the version name and the required fields I pasted. If a field is not on the list, do not add it. Do not invent a newer version name.”

What not to delegate

Do not let the model bump the version because a response looked richer. Do not keep two field lists under one name. Do not treat a green example in chat as proof the consumer accepts it. Run the validator you already have, and record the version it accepted.

FAQ

How is this different from a schema lock?

The lock stops a bad payload from leaving. The version is the name of the shape the lock checks. You can have a version with no lock, which means bad payloads still ship with a confident name. You can have a lock with no version, which means callers cannot tell which contract they passed.

How is this different from a tool result schema?

A tool result schema describes what a tool returns to the model. A response schema version describes what your system returns to a caller. They can both be JSON. They are not the same contract. Do not reuse the name.

Can one version add an optional field?

Only if you wrote that the field is optional, and older consumers are allowed to ignore it. If a consumer will break without the field, it is required, and it belongs in a new version name. The model does not get to call a break “optional.”

Who may retire a version?

The owner of the consumer list. Retiring means you named the date and the replacement version. A prompt that stops mentioning the old name has not retired it. Callers still on the old name need the date in writing.

Last verified

October 24, 2026 for Claude and for ChatGPT’s plan page. October 16, 2026 for Cursor Plus and GitHub Copilot. Published October 24, 2026.

Sources: Claude pricing, ChatGPT and Codex pricing, Cursor pricing, GitHub Copilot.

Published by Andrew for AI Tools Optimizer.

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