Follow Discord
Sweep 10 Nov 2026 · 02:18Z Build v2.1.322 539 read Stable v2.1.311 Latest v2.1.322 Next v2.1.322 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeDocsClaude Developer Platform 9 Nov 2026
One change · api

token-counting changedbuild-with-claude/token-counting

Nearest release: v2.1.321, published under an hour after this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

Recorded here
Lines+1added
Lines−1removed
From line 1,425 where the diff opens
First seen 14 Aug 2026 this site's first read of the page
Recorded edits27to this page, all time

The whole hunk

from line 1425, old and new numbered
/
lines
from line 1425
14251425 
14261426## Token counts on Claude Fable and Claude Mythos models
14271427 
1428Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, and Claude Mythos 5 share the tokenizer introduced with Claude Opus 4.7. A prompt counts the same on all four, and roughly 30 percent higher than on models before Claude Opus 4.7 (the exact increase depends on the content). The token counting endpoint counts under the tokenizer of the `model` you pass. To measure the difference for your workload, count the same request twice, once with your current model and once with the model you plan to move to, and compare the two `input_tokens` values.
1428Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, and Claude Mythos 5 share the tokenizer introduced with Claude Opus 4.7. A prompt counts the same on all four, and roughly 30 percent higher than on models before Claude Opus 4.7 (the exact increase depends on the content). The token counting endpoint counts under the tokenizer of the `model` you pass. To measure the difference for your workload, count the same request once with your current model and once with the model you plan to move to. Then compare the two `input_tokens` values.
14291429 
14301430<Note>
14311431 **Billing and migration:** Usage and billing on these models reflect this tokenizer’s counts. When migrating from a model before Claude Opus 4.7, don’t reuse token counts measured on the older model to estimate costs or context window fit. Count your prompts with the `model` ID you plan to use (for example, `"claude-fable-5-1"`).
Feedback