Thinking — skyl

Thinking asks the model to reason before answering. Support varies more here than anywhere else in skyl, so the per-provider table below is the important part of this page.

Reference#

type Thinking struct { Enabled bool Effort Effort }

Parameters

Enabled — requests reasoning.
Effort — hints at depth: low, medium, high, max. Empty means the provider's default.

Caveats

A nil *Thinking and &Thinking{} mean different things. Nil is "provider default"; the zero value is "explicitly off".
On Anthropic, Effort does nothing. The SDK's adaptive thinking config has no budget or effort field, so there is nothing to map it onto.
On OpenAI and openaicompat, Thinking is ignored unless both Enabled and Effort are set. So &Thinking{Enabled: false} does nothing there.
Effort: max is sent literally to OpenAI, which does not define that value — expect a 400.
Only Gemini maps every case, including a zero budget.

What each adapter does#

Value	anthropic	openai / compat	gemini
nil	nothing sent	nothing sent	nothing sent
{Enabled: true}	thinking: adaptive	ignored	budget -1 (model decides)
{Enabled: false}	thinking: disabled	ignored	budget 0
… Effort: low	effort ignored	reasoning_effort: low	budget 1024
… Effort: medium	effort ignored	medium	budget 8192
… Effort: high	effort ignored	high	budget 16384
… Effort: max	effort ignored	sent — undefined by OpenAI	budget 24576

Usage#

Asking for deep reasoning

goCompiles

req.Thinking = &skyl.Thinking{Enabled: true, Effort: skyl.EffortHigh}

req.Thinking = &skyl.Thinking{Enabled: true, Effort: skyl.EffortHigh}

Turning reasoning off, portably

goCompiles

req.Thinking = &skyl.Thinking{Enabled: false} // works on anthropic and gemini

if provider == "openai" || provider == "openai-compatible" {
	// The adapter ignores Thinking without an Effort, so reach the wire field.
	if req.ProviderOptions == nil {
		req.ProviderOptions = map[string]any{}
	}
	req.ProviderOptions["reasoning_effort"] = "minimal"
}

req.Thinking = &skyl.Thinking{Enabled: false} // works on anthropic and gemini

if provider == "openai" || provider == "openai-compatible" {
	// The adapter ignores Thinking without an Effort, so reach the wire field.
	if req.ProviderOptions == nil {
		req.ProviderOptions = map[string]any{}
	}
	req.ProviderOptions["reasoning_effort"] = "minimal"
}

Setting a precise budget on Anthropic

goCompiles

// Effort is ignored there, but the budget is reachable by JSON path —
// which only Anthropic supports.
req.ProviderOptions = map[string]any{"thinking.budget_tokens": 4096}

// Effort is ignored there, but the budget is reachable by JSON path —
// which only Anthropic supports.
req.ProviderOptions = map[string]any{"thinking.budget_tokens": 4096}

Troubleshooting#

Turning reasoning off had no effect on cost

You are on OpenAI, where &Thinking{Enabled: false} is ignored entirely. Send reasoning_effort through ProviderOptions.

Effort makes no difference on Anthropic

It is dropped. Use ProviderOptions with thinking.budget_tokens.

Where is the reasoning in the response?

Dropped from Message by every adapter; it stays in Response.Raw. Streaming on Anthropic emits EventThinkingDelta, and is the only structured access skyl offers.