Verified July 27, 2026
Claude Fable 5 in Windsurf
Other tools give you a model and an effort parameter. Windsurf gives you five models. The difference shows up on your bill.
The short answer
Supported, no configuration needed — but read the model list carefully. Windsurf exposes Claude Fable 5 as five separate picker entries, one per effort level, and the credit cost more than doubles from Low to Max. Pick the entry, not just the model. Free-tier accounts cannot reach Fable 5 at all.
Support status
Supported, verified against Windsurf's official model documentation on July 27, 2026. Claude Fable 5 Medium appears in the self-serve token pricing table at $10 per million input, $1 per million cached input and $50 per million output — the same numbers Anthropic charges. The legacy credit-based enterprise plans list five distinct entries: Fable 5 Low Thinking at 40 credits, Medium at 50, High at 70, XHigh at 80 and Max at 100, all currently marked as promotional pricing. The same models are available in Devin Desktop and Devin CLI. Free-tier accounts are limited to SWE-1.6.
Setup
There is no config file. All four decisions happen in the model dropdown and the billing page.
- 1
Open the Cascade model selector
The dropdown sits directly under the Cascade conversation input box. Windsurf's docs point at the model selector inside the IDE as the source of truth for what is currently available and what it costs, because the catalogue and promotional pricing both change faster than the docs page.
- 2
Choose an effort tier, not just the model
Fable 5 Low, Medium, High, XHigh and Max are five separate entries. On credit-billed plans they cost 40, 50, 70, 80 and 100 credits respectively. Anthropic's own guidance is that Fable 5 at lower effort still performs well and often exceeds the xhigh performance of previous models, so Medium is a genuine default rather than a compromise.
- 3
Confirm which billing model you are on
Windsurf's docs split pricing three ways: self-serve plans billed on token cost, newer enterprise plans billed in ACUs, and legacy enterprise plans billed in credits. Only the legacy credit tab exposes the per-effort credit numbers, so the cost of moving from Medium to Max is visible on some plans and invisible on others.
- 4
Check whether BYOK is open to your plan
Third-party guides report that Free and Pro accounts can attach their own Anthropic key while Teams and Enterprise are metered instead — we could not confirm BYOK for Fable 5 specifically in Windsurf's official docs as of July 27, 2026, so treat this as a check-in-your-account item rather than a documented guarantee.
Gotchas
Consequences of treating effort as a model rather than a parameter.
Adaptive will not necessarily route to Fable 5
Adaptive is Windsurf's recommended default and picks a model per prompt at variable per-request pricing. That is the right choice for most work and the wrong one when you are specifically benchmarking or debugging Fable 5 behaviour, because you cannot tell from the transcript which model answered. Select the model explicitly when the answer needs to be attributable.
Changing effort mid-conversation costs you the cache
Anthropic documents that the resolved effort value is rendered into the prompt, so changing it invalidates cache breakpoints exactly the way changing the legacy budget_tokens parameter did. In Windsurf that looks like switching picker entries mid-thread, which feels lightweight but re-bills your whole accumulated context at full input price.
Free tier cannot reach Fable 5
Windsurf's docs are explicit that free-tier users only have access to SWE-1.6. If you are evaluating Fable 5 for a team, do it on a paid seat — an empty model dropdown on a free account is a plan limit, not an outage.
Cost notes
On self-serve plans Windsurf passes Anthropic's pricing through unchanged: $10 per million input, $1 cached, $50 output. On legacy credit plans the effort ladder is where the money goes — Max at 100 credits is double Medium at 50 for the same underlying model, and 2.5x the 40 credits of Low. Since Anthropic itself says lower effort on Fable 5 often beats xhigh on previous models, defaulting to the Max entry is usually paying double for headroom you are not using. Note that the Fable 5 credit rates are flagged as promotional and can change.
Find the effort level that is actually enough
Our effort guide walks through what each level changes in the model's behaviour, and how to run a sweep so the choice is measured rather than guessed.