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Final Pass

Final Pass runs your own prompt on alt text AltText.ai has already generated, so your wording gets the last word. Use it to make wording, tone, or structure more consistent without changing how the image itself is analyzed. Formerly called ChatGPT Modification.

Use the exact placeholder

Every nonblank Final Pass prompt must include {{AltText}} exactly as shown. The placeholder is case-sensitive and includes two opening and two closing braces. AltText.ai replaces it with the generated text before applying the prompt.

Preserve every fact and rewrite in a concise, neutral tone: {{AltText}}

Changing the capitalization, number of braces, or adding spaces inside the placeholder makes it invalid.

Write the prompt in English

Write the prompt itself in English on every surface, even when the alt text is generated in another language. Keywords and negative keywords follow the same rule. Pick the output language with the language setting or the lang parameter, not by writing the prompt in that language.

Rewrite in a concise, neutral tone: {{AltText}}

A prompt written in the target language is not a supported input, and the result is unpredictable rather than a clear error.

Limits and precedence

The limit applies to the entire prompt, including the {{AltText}} placeholder.

Surface Prompt limit Required token Which prompt is used
Account Settings 500 characters in the current UI {{AltText}} The account default is used when a request or integration does not provide its own prompt.
One-off website or API request 768 characters {{AltText}} A prompt supplied with the request overrides the account default. A blank or omitted value falls back to the account default.
Shopify 768 characters {{AltText}} A nonblank store prompt overrides the account default. A blank store prompt falls back to the account default.
WordPress 512 bytes {{AltText}} A nonblank site prompt overrides the account default. A blank site prompt falls back to the account default.

Set an account default under Account → Settings → Alt Text Generation when you want the same rewrite across surfaces. Set a request, store, or site prompt when that workflow needs different instructions. If neither is set, AltText.ai skips the Final Pass rewrite.

What the prompt receives

Generation happens in this order:

  1. AltText.ai analyzes the image and generates an initial description.
  2. Optional keyword and ecommerce processing updates that description.
  3. AltText.ai substitutes the current description for {{AltText}} and sends that text through the Final Pass rewrite.

The Final Pass step never receives the image. It is a text rewrite, not a second image-analysis pass. It therefore cannot reliably invent a color, product name, market, currency, model number, or other fact missing from the text it receives. Provide known product data through the ecommerce or keyword options where available, and ask the prompt to preserve facts.

Good prompt patterns include:

Use a warm outdoor-brand voice without adding facts: {{AltText}}

Lead with details already present and preserve visible facts: {{AltText}}

Avoid instructions that ask the rewrite to guess details it cannot verify.

Output length

Where a maximum-output setting is available in AltText.ai or Shopify, the accepted target is 80–500 characters. AltText.ai instructs the provider to honor that target and retries or shortens an over-limit response. A provider failure during those attempts can still leave text over the requested target, so treat the setting as an enforced target rather than a guarantee in every failure mode.

Stored alt text has a separate hard ceiling of 1,024 characters. Output over that ceiling is rejected rather than saved.

WordPress byte limit and invalid input

The WordPress limit is 512 bytes, not 512 visible characters. Smart quotes, emoji, and many non-English characters use more than one byte, so a prompt can exceed the limit before it reaches 512 visible characters.

WordPress currently clears the saved Final Pass prompt when submitted input is over 512 bytes or does not contain the exact {{AltText}} placeholder. It does not show a useful validation error. If the field is unexpectedly blank after saving, shorten the prompt, replace multibyte punctuation where practical, and confirm the placeholder's capitalization and braces before saving again.