Cohere Go SDK Reference
Official Resources
Installation
go get github.com/cohere-ai/cohere-go/v2
Client Setup
package main
import (
"context"
cohere "github.com/cohere-ai/cohere-go/v2"
client "github.com/cohere-ai/cohere-go/v2/client"
)
func main() {
// Option 1: Auto-read from CO_API_KEY env var
co := client.NewClient()
// Option 2: Explicit API key
co := client.NewClient(
client.WithToken("your-api-key"),
)
// Option 3: Custom endpoint
co := client.NewClient(
client.WithToken("your-api-key"),
client.WithBaseURL("https://your-deployment.com"),
)
}
Chat API
Basic Chat
ctx := context.Background()
response, err := co.V2.Chat(ctx, &cohere.V2ChatRequest{
Model: "command-a-03-2025",
Messages: []*cohere.ChatMessageV2{
{
Role: "user",
User: &cohere.UserMessage{
Content: &cohere.UserMessageContent{
String: cohere.String("What is machine learning?"),
},
},
},
},
})
if err != nil {
log.Fatal(err)
}
fmt.Println(response.Message.Content[0].Text)
With System Message
response, err := co.V2.Chat(ctx, &cohere.V2ChatRequest{
Model: "command-a-03-2025",
Messages: []*cohere.ChatMessageV2{
{
Role: "system",
System: &cohere.SystemMessage{
Content: cohere.String("You are a helpful coding assistant."),
},
},
{
Role: "user",
User: &cohere.UserMessage{
Content: &cohere.UserMessageContent{
String: cohere.String("Write a Go hello world"),
},
},
},
},
})
Parameters
temperature := 0.7
maxTokens := 500
response, err := co.V2.Chat(ctx, &cohere.V2ChatRequest{
Model: "command-a-03-2025",
Messages: messages,
Temperature: &temperature,
MaxTokens: &maxTokens,
P: cohere.Float64(0.9),
K: cohere.Int(50),
Seed: cohere.Int(42),
StopSequences: []string{"END"},
})
Streaming
stream, err := co.V2.ChatStream(ctx, &cohere.V2ChatStreamRequest{
Model: "command-a-03-2025",
Messages: []*cohere.ChatMessageV2{
{
Role: "user",
User: &cohere.UserMessage{
Content: &cohere.UserMessageContent{
String: cohere.String("Write a poem"),
},
},
},
},
})
if err != nil {
log.Fatal(err)
}
defer stream.Close()
for {
event, err := stream.Recv()
if err != nil {
break
}
switch event.Type {
case "content-delta":
if event.Delta != nil && event.Delta.Message != nil {
fmt.Print(event.Delta.Message.Content.Text)
}
case "message-end":
fmt.Println("\nGeneration complete")
}
}
Embeddings
Basic Embedding
response, err := co.V2.Embed(ctx, &cohere.V2EmbedRequest{
Model: "embed-v4.0",
Texts: []string{"Hello world", "Machine learning"},
InputType: cohere.EmbedInputTypeSearchDocument.Ptr(),
EmbeddingTypes: []cohere.EmbeddingType{cohere.EmbeddingTypeFloat},
})
if err != nil {
log.Fatal(err)
}
embeddings := response.Embeddings.Float
fmt.Printf("Dimensions: %d\n", len(embeddings[0]))
Input Types (CRITICAL)
// For STORING documents
docResponse, err := co.V2.Embed(ctx, &cohere.V2EmbedRequest{
Model: "embed-v4.0",
Texts: documents,
InputType: cohere.EmbedInputTypeSearchDocument.Ptr(), // MUST use
EmbeddingTypes: []cohere.EmbeddingType{cohere.EmbeddingTypeFloat},
})
// For QUERYING
queryResponse, err := co.V2.Embed(ctx, &cohere.V2EmbedRequest{
Model: "embed-v4.0",
Texts: []string{userQuery},
InputType: cohere.EmbedInputTypeSearchQuery.Ptr(), // MUST use
EmbeddingTypes: []cohere.EmbeddingType{cohere.EmbeddingTypeFloat},
})
Reranking
topN := 3
response, err := co.V2.Rerank(ctx, &cohere.V2RerankRequest{
Model: "rerank-v4.0-pro",
Query: "What is machine learning?",
Documents: []*cohere.RerankRequestDocumentsItem{
{String: cohere.String("Machine learning is a subset of AI...")},
{String: cohere.String("The weather is sunny today...")},
{String: cohere.String("Deep learning uses neural networks...")},
},
TopN: &topN,
})
if err != nil {
log.Fatal(err)
}
for _, result := range response.Results {
fmt.Printf("Index: %d, Score: %.4f\n", result.Index, result.RelevanceScore)
}
Tool Use
Define Tools
tools := []*cohere.ToolV2{
{
Type: cohere.String("function"),
Function: &cohere.ToolV2Function{
Name: cohere.String("get_weather"),
Description: cohere.String("Get current weather for a location"),
Parameters: map[string]interface{}{
"type": "object",
"properties": map[string]interface{}{
"location": map[string]interface{}{
"type": "string",
"description": "City name",
},
},
"required": []string{"location"},
},
},
},
}
Execute Tool Calls
func runWithTools(ctx context.Context, co *client.Client, userMessage string) (string, error) {
messages := []*cohere.ChatMessageV2{
{
Role: "user",
User: &cohere.UserMessage{
Content: &cohere.UserMessageContent{
String: cohere.String(userMessage),
},
},
},
}
response, err := co.V2.Chat(ctx, &cohere.V2ChatRequest{
Model: "command-a-03-2025",
Messages: messages,
Tools: tools,
})
if err != nil {
return "", err
}
for len(response.Message.ToolCalls) > 0 {
messages = append(messages, &cohere.ChatMessageV2{
Role: "assistant",
Assistant: &cohere.AssistantMessage{
ToolPlan: response.Message.ToolPlan,
ToolCalls: response.Message.ToolCalls,
},
})
for _, tc := range response.Message.ToolCalls {
var args map[string]interface{}
json.Unmarshal([]byte(*tc.Function.Arguments), &args)
result := functionsMap[*tc.Function.Name](args)
resultJSON, _ := json.Marshal(result)
messages = append(messages, &cohere.ChatMessageV2{
Role: "tool",
Tool: &cohere.ToolMessage{
ToolCallId: tc.Id,
Content: []*cohere.ToolContent{
{
Type: cohere.String("document"),
Document: &cohere.Document{
Data: map[string]string{"result": string(resultJSON)},
},
},
},
},
})
}
response, err = co.V2.Chat(ctx, &cohere.V2ChatRequest{
Model: "command-a-03-2025",
Messages: messages,
Tools: tools,
})
if err != nil {
return "", err
}
}
return *response.Message.Content[0].Text, nil
}
Error Handling
import (
"errors"
core "github.com/cohere-ai/cohere-go/v2/core"
)
response, err := co.V2.Chat(ctx, request)
if err != nil {
var apiErr *core.APIError
if errors.As(err, &apiErr) {
fmt.Printf("API Error: %d - %s\n", apiErr.StatusCode, apiErr.Message)
} else {
fmt.Printf("Error: %v\n", err)
}
return
}
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