migrate from old tool solution to native anthropic structured output

services/anthropic/llm.go

@@ -7,15 +7,16 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/modfin/bellman/models"
-	"github.com/modfin/bellman/models/gen"
-	"github.com/modfin/bellman/prompt"
-	"github.com/modfin/bellman/tools"
 	"io"
 	"log"
 	"net/http"
 	"strings"
 	"sync/atomic"
+
+	"github.com/modfin/bellman/models"
+	"github.com/modfin/bellman/models/gen"
+	"github.com/modfin/bellman/prompt"
+	"github.com/modfin/bellman/tools"
 )
 
 var requestNo int64
@@ -59,6 +60,7 @@ func (g *generator) Stream(conversation ...prompt.Prompt) (<-chan *gen.StreamRes
 
 	if resp.StatusCode != http.StatusOK {
 		b, err := io.ReadAll(resp.Body)
+		_ = resp.Body.Close()
 		return nil, errors.Join(fmt.Errorf("unexpected status code, %d, err: {%s}", resp.StatusCode, string(b)), err)
 	}
 
@@ -180,28 +182,17 @@ func (g *generator) Stream(conversation ...prompt.Prompt) (<-chan *gen.StreamRes
 			}
 			if ss.Delta != nil {
 				if len(toolID) > 0 && len(toolName) > 0 && ss.Delta.PartialJSON != nil {
-					if toolName == respone_output_callback_name {
-						// If the tool is the output callback, we just send the partial JSON as text
-						stream <- &gen.StreamResponse{
-							Type:    gen.TYPE_DELTA,
-							Role:    prompt.AssistantRole,
-							Index:   ss.Index,
-							Content: *ss.Delta.PartialJSON,
-						}
-					} else {
-						stream <- &gen.StreamResponse{
-							Type:  gen.TYPE_DELTA,
-							Role:  prompt.ToolCallRole,
-							Index: ss.Index,
-							ToolCall: &tools.Call{
-								ID:       toolID,
-								Name:     toolName,
-								Argument: []byte(*ss.Delta.PartialJSON),
-								Ref:      reqModel.toolBelt[toolName],
-							},
-						}
+					stream <- &gen.StreamResponse{
+						Type:  gen.TYPE_DELTA,
+						Role:  prompt.ToolCallRole,
+						Index: ss.Index,
+						ToolCall: &tools.Call{
+							ID:       toolID,
+							Name:     toolName,
+							Argument: []byte(*ss.Delta.PartialJSON),
+							Ref:      reqModel.toolBelt[toolName],
+						},
 					}
-
 				}
 				if ss.Delta.Text != nil && len(*ss.Delta.Text) > 0 {
 					stream <- &gen.StreamResponse{
@@ -306,12 +297,6 @@ func (g *generator) Prompt(conversation ...prompt.Prompt) (*gen.Response, error)
 		}
 	}
 
-	// This is really an output schema callback. So lets just transform it to Text
-	if len(res.Tools) == 1 && res.Tools[0].Name == respone_output_callback_name {
-		res.Texts = []string{string(res.Tools[0].Argument)}
-		res.Tools = nil
-	}
-
 	g.anthropic.log("[gen] response",
 		"request", reqc,
 		"model", g.request.Model.FQN(),
@@ -344,16 +329,12 @@ func (g *generator) prompt(conversation ...prompt.Prompt) (*http.Request, reques
 	}
 
 	if g.request.OutputSchema != nil {
-		model.Tools = []reqTool{
-			{
-				Name:        respone_output_callback_name,
-				Description: "function that is called with the result of the llm query",
-				InputSchema: fromBellmanSchema(g.request.OutputSchema),
+		model.OutputConfig = &reqOutputConfig{
+			Format: &reqOutputFormat{
+				Type:   "json_schema",
+				Schema: sanitizeForStructuredOutput(fromBellmanSchema(g.request.OutputSchema)),
 			},
 		}
-		model.Tool = &reqToolChoice{
-			Type: "any",
-		}
 	}
 
 	if len(g.request.Tools) > 0 {
@@ -368,29 +349,19 @@ func (g *generator) prompt(conversation ...prompt.Prompt) (*http.Request, reques
 	}
 
 	if g.request.ToolConfig != nil {
-		_name := ""
-		_type := ""
-
+		var choice *reqToolChoice
 		switch g.request.ToolConfig.Name {
 		case tools.NoTool.Name:
+			choice = &reqToolChoice{Type: "none"}
 		case tools.AutoTool.Name:
-			_type = "auto"
+			choice = &reqToolChoice{Type: "auto"}
 		case tools.RequiredTool.Name:
-			_type = "any"
+			choice = &reqToolChoice{Type: "any"}
 		default:
-			_type = "tool"
-			_name = g.request.ToolConfig.Name
+			choice = &reqToolChoice{Type: "auto"}
 		}
-		if model.Tool != nil {
-			model.Tool = &reqToolChoice{
-				Type: _type, // // "auto, any, tool"
-				Name: _name,
-			}
-		}
-
-		if g.request.ToolConfig.Name == tools.NoTool.Name { // None is not supporded by Anthropic, so lets just remove the toolks.
-			model.Tool = nil
-			model.Tools = nil
+		if len(model.Tools) > 0 {
+			model.Tool = choice
 		}
 	}
 

services/anthropic/models.go

@@ -8,19 +8,6 @@ const Provider = "Anthropic"
 
 const Version = "2023-06-01"
 
-//curl https://api.anthropic.com/v1/models/claude-3-5-sonnet-20241022 \
-//  --header "x-api-key: $ANTHROPIC_API_KEY" \
-//  --header "anthropic-version: 2023-06-01"
-//{
-//  "data": [
-//    {
-//      "type": "model",
-//      "id": "claude-3-5-sonnet-20241022",
-//      "display_name": "Claude 3.5 Sonnet (New)",
-//      "created_at": "2024-10-22T00:00:00Z"
-//    },
-//	{...
-
 //type GenModel string
 
 // https://docs.anthropic.com/en/docs/about-claude/models
@@ -43,25 +30,31 @@ var GenModel_4_0_sonnet_20250514 = gen.Model{
 	OutputMaxToken: 64_000,
 }
 var GenModel_4_5_sonnet_latest = gen.Model{
-	Provider:       Provider,
-	Description:    "Our smartest model for complex agents and coding",
-	Name:           "claude-4-5-sonnet",
-	InputMaxToken:  200_000,
-	OutputMaxToken: 64_000,
+	Provider:                Provider,
+	Description:             "Our smartest model for complex agents and coding",
+	Name:                    "claude-4-5-sonnet",
+	InputMaxToken:           200_000,
+	OutputMaxToken:          64_000,
+	SupportTools:            true,
+	SupportStructuredOutput: true,
 }
 var GenModel_4_5_sonnet_20250929 = gen.Model{
-	Provider:       Provider,
-	Description:    "Our smartest model for complex agents and coding",
-	Name:           "claude-sonnet-4-5-20250929",
-	InputMaxToken:  200_000,
-	OutputMaxToken: 64_000,
+	Provider:                Provider,
+	Description:             "Our smartest model for complex agents and coding",
+	Name:                    "claude-sonnet-4-5-20250929",
+	InputMaxToken:           200_000,
+	OutputMaxToken:          64_000,
+	SupportTools:            true,
+	SupportStructuredOutput: true,
 }
 var GenModel_4_6_sonnet_latest = gen.Model{
-	Provider:       Provider,
-	Name:           "claude-sonnet-4-6",
-	Description:    "The best combination of speed and intelligence",
-	InputMaxToken:  1_000_000,
-	OutputMaxToken: 64_000,
+	Provider:                Provider,
+	Name:                    "claude-sonnet-4-6",
+	Description:             "The best combination of speed and intelligence",
+	InputMaxToken:           1_000_000,
+	OutputMaxToken:          64_000,
+	SupportTools:            true,
+	SupportStructuredOutput: true,
 }
 var GenModel_3_5_sonnet_latest = gen.Model{
 	Provider:                Provider,
@@ -94,17 +87,6 @@ var GenModel_3_5_sonnet_20240620 = gen.Model{
 	SupportStructuredOutput: false,
 }
 
-//var GenModel_3_sonnet_20240229 = gen.Model{
-//	Provider:                Provider,
-//	Name:                    "claude-3-sonnet-20240229",
-//	Description:             "",
-//	InputContentTypes:       nil,
-//	InputMaxToken:           0,
-//	OutputMaxToken:          0,
-//	SupportTools:            false,
-//	SupportStructuredOutput: false,
-//}
-
 var GenModel_4_5_haiku_latest = gen.Model{
 	Provider:                Provider,
 	Name:                    "claude-haiku-4-5",
@@ -146,37 +128,6 @@ var GenModel_3_5_haiku_20241022 = gen.Model{
 	SupportTools:            false,
 	SupportStructuredOutput: false,
 }
-var GenModel_3_haiku_20240307 = gen.Model{
-	Provider:                Provider,
-	Name:                    "claude-3-haiku-20240307",
-	Description:             "",
-	InputContentTypes:       nil,
-	InputMaxToken:           0,
-	OutputMaxToken:          0,
-	SupportTools:            false,
-	SupportStructuredOutput: false,
-}
-
-var GenModel_3_opus_latest = gen.Model{
-	Provider:                Provider,
-	Name:                    "claude-3-opus-latest",
-	Description:             "",
-	InputContentTypes:       nil,
-	InputMaxToken:           0,
-	OutputMaxToken:          0,
-	SupportTools:            false,
-	SupportStructuredOutput: false,
-}
-var GenModel_3_opus_20240229 = gen.Model{
-	Provider:                Provider,
-	Name:                    "claude-3-opus-20240229",
-	Description:             "",
-	InputContentTypes:       nil,
-	InputMaxToken:           0,
-	OutputMaxToken:          0,
-	SupportTools:            false,
-	SupportStructuredOutput: false,
-}
 var GenModel_4_0_opus_20250514 = gen.Model{
 	Provider:                Provider,
 	Name:                    "claude-opus-4-20250514",
@@ -198,20 +149,29 @@ var GenModel_4_1_opus_20250805 = gen.Model{
 	SupportStructuredOutput: false,
 }
 var GenModel_4_6_opus_latest = gen.Model{
-	Provider:       Provider,
-	Name:           "claude-opus-4-6",
-	Description:    "The most intelligent model for building agents and coding",
-	InputMaxToken:  1_000_000,
-	OutputMaxToken: 128_000,
+	Provider:                Provider,
+	Name:                    "claude-opus-4-6",
+	Description:             "The most intelligent model for building agents and coding",
+	InputMaxToken:           1_000_000,
+	OutputMaxToken:          128_000,
+	SupportTools:            true,
+	SupportStructuredOutput: true,
+}
+var GenModel_4_7_opus_latest = gen.Model{
+	Provider:                Provider,
+	Name:                    "claude-opus-4-7",
+	Description:             "The most intelligent model for building agents and coding",
+	InputMaxToken:           1_000_000,
+	OutputMaxToken:          128_000,
+	SupportTools:            true,
+	SupportStructuredOutput: true,
 }
 
 var GenModels = map[string]gen.Model{
 	GenModel_3_5_sonnet_latest.Name:   GenModel_3_5_sonnet_latest,
 	GenModel_3_5_sonnet_20241022.Name: GenModel_3_5_sonnet_20241022,
-	//GenModel_3_5_sonnet_20240620.Name: GenModel_3_5_sonnet_20240620,
-	GenModel_3_5_haiku_latest.Name:   GenModel_3_5_haiku_latest,
-	GenModel_3_5_haiku_20241022.Name: GenModel_3_5_haiku_20241022,
-	//GenModel_3_haiku_20240307.Name:    GenModel_3_haiku_20240307,
-	GenModel_4_6_opus_latest.Name:   GenModel_4_6_opus_latest,
-	GenModel_4_6_sonnet_latest.Name: GenModel_4_6_sonnet_latest,
+	GenModel_3_5_haiku_latest.Name:    GenModel_3_5_haiku_latest,
+	GenModel_3_5_haiku_20241022.Name:  GenModel_3_5_haiku_20241022,
+	GenModel_4_6_opus_latest.Name:     GenModel_4_6_opus_latest,
+	GenModel_4_6_sonnet_latest.Name:   GenModel_4_6_sonnet_latest,
 }

services/anthropic/request.go

@@ -27,9 +27,22 @@ type request struct {
 
 	Thinking *reqExtendedThinking `json:"thinking,omitempty"`
 
+	// OutputConfig enables native structured outputs (GA Nov 2025).
+	// https://platform.claude.com/docs/en/build-with-claude/structured-outputs
+	OutputConfig *reqOutputConfig `json:"output_config,omitempty"`
+
 	toolBelt map[string]*tools.Tool
 }
 
+type reqOutputConfig struct {
+	Format *reqOutputFormat `json:"format,omitempty"`
+}
+
+type reqOutputFormat struct {
+	Type   string      `json:"type"` // "json_schema"
+	Schema *JSONSchema `json:"schema,omitempty"`
+}
+
 type reqMessages struct {
 	Role    string       `json:"role"` // assistant or user
 	Content []reqContent `json:"content"`

services/anthropic/response.go

@@ -1,7 +1,5 @@
 package anthropic
 
-const respone_output_callback_name = "__bellman__result_callback"
-
 type anthropicResponse struct {
 	Content []struct {
 		Type     string `json:"type"` // text or tool_use

services/anthropic/schema.go

@@ -126,3 +126,55 @@ func fromBellmanSchema(bellmanSchema *schema.JSON) *JSONSchema {
 
 	return def
 }
+
+// sanitizeForStructuredOutput mutates s (and descendants) in place to satisfy
+// Anthropic's native structured-outputs constraints: every object must set
+// additionalProperties: false, and numeric/array-size constraints are
+// unsupported and must be stripped. minItems is clamped to {0, 1}.
+func sanitizeForStructuredOutput(s *JSONSchema) *JSONSchema {
+	if s == nil {
+		return nil
+	}
+
+	if isObjectType(s.Type) && s.AdditionalProperties == nil {
+		s.AdditionalProperties = false
+	}
+
+	s.Minimum = 0
+	s.Maximum = 0
+	s.MaxItems = 0
+	if s.MinItems > 1 {
+		s.MinItems = 1
+	}
+
+	for k, prop := range s.Properties {
+		sanitizeForStructuredOutput(&prop)
+		s.Properties[k] = prop
+	}
+	sanitizeForStructuredOutput(s.Items)
+	for _, d := range s.Defs {
+		sanitizeForStructuredOutput(d)
+	}
+	if nested, ok := s.AdditionalProperties.(JSONSchema); ok {
+		sanitizeForStructuredOutput(&nested)
+		s.AdditionalProperties = nested
+	}
+
+	return s
+}
+
+func isObjectType(t any) bool {
+	switch v := t.(type) {
+	case DataType:
+		return v == Object
+	case string:
+		return v == string(Object)
+	case []any:
+		for _, x := range v {
+			if isObjectType(x) {
+				return true
+			}
+		}
+	}
+	return false
+}