Cause (Documented platform behavior): Documented: the flag turns silent downscaling into a rejection; limit depends on the model tier (1920x1080 fits the high-res tier but not standard); hard 8000px and many-image limits are separate rejections.
Fix status: documented_behavior
Limitations:
- Tool-result screenshots for computer/browser use are never auto-resized; they are rejected regardless.
Evidence (public sources, summarized; not reproduced by this contributor):
- https://platform.claude.com/docs/en/build-with-claude/vision-coordinates (official_docs, 2026-09, documented_behavior): Docs quote the exact rejection message, note the check considers every model named on the request, that URL/file-ID rejections omit the position, and that undeterminable dimensions are rejected with a different message.
Search phrasings: oversized_image error anthropic; exceed the maximum image size of a model named on this request; anthropic image would be downsized error
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Coordinate/computer-use style workflows get invalid_request_error for a screenshot that works without the flag; URL/file-ID images fail with the same message but no messages.N.content.M position.
- Context
- Product: Anthropic Claude API Component: vision image transformations (oversized_image) Operation: messages.create / count_tokens with image block transformations.oversized_image = "error" Affected versions: unknown Environment: unknown HTTP status: 400 Trigger: Image block marked oversized_image: 'error' whose dimensions exceed the smallest limit of every model named on the request (including fallbacks); images whose dimensions cannot be determined are also rejected.
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- image dimensions 1920x1080 exceed the maximum image size of a model named on this request and would be downsized to 1456x819; scale the image to at most 1456x819 or set the image's oversized_image setting to "downsize"
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [Anthropic vision] 400 'image dimensions WxH exceed the maximum image size of a model named on this request and would be downsized' with oversized_image: "error"
Recommended action: Pre-resize to the dimensions quoted in the error (or drop the flag and map coordinates yourself); use count_tokens to pre-check embedded images (it honors transformations but rejects URL/file sources).
Option: Resize before sending or accept downsize [evidence: official_recommended_action]
Applies when: Anthropic Claude API / vision image transformations (oversized_image)
Steps:
1. Read the max dimensions from the error
2. Resize the image client-side to fit
3. Keep the scale factor to map returned coordinates back
4. Or set oversized_image to 'downsize'
Expected: Request accepted / failure becomes diagnosable
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- 7dcf5135-1ee7-4593-99da-c5ceb104abf1
- Proposed action
- Recommended action: Pre-resize to the dimensions quoted in the error (or drop the flag and map coordinates yourself); use count_tokens to pre-check embedded images (it honors transformations but rejects URL/file sources). Option: Resize before sending or accept downsize [evidence: official_recommended_action] Applies when: Anthropic Claude API / vision image transformations (oversized_image) Steps: 1. Read the max dimensions from the error 2. Resize the image client-side to fit 3. Keep the scale factor to map returned coordinates back 4. Or set oversized_image to 'downsize' Expected: Request accepted / failure becomes diagnosable
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.