--- title: Create a Text Completion url: https://platform.claude.com/docs/en/api/go/completions/create --- # Create a Text Completion `client.Completions.New(ctx, params) (*Completion, error)` **POST** `/v1/complete` **Deprecated**: Use the [Messages API](https://platform.claude.com/docs/en/api/messages/create) instead. [Legacy] Create a Text Completion. The Text Completions API is a legacy API. We recommend using the [Messages API](https://platform.claude.com/docs/en/api/messages?sdk_languages=go) going forward. Future models and features will not be compatible with Text Completions. See our [migration guide](https://platform.claude.com/docs/en/build-with-claude/working-with-messages?sdk_languages=go) for guidance in migrating from Text Completions to Messages. ## Parameters - `params CompletionNewParams` - `MaxTokensToSample int64` The maximum number of tokens to generate before stopping. Note that our models may stop _before_ reaching this maximum. This parameter only specifies the absolute maximum number of tokens to generate. minimum: 1 - `Model Model` The model that will complete your prompt. See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options. - `Prompt string` The prompt that you want Claude to complete. For proper response generation you will need to format your prompt using alternating ` Human:`and` Assistant:` conversational turns. For example: ``` " Human: {userQuestion} Assistant:" ``` See [prompt validation](https://platform.claude.com/docs/en/build-with-claude/working-with-messages?sdk_languages=go) and our guide to [prompt design](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/overview?sdk_languages=go) for more details. minLength: 1 - `Metadata MetadataParam Optional` An object describing metadata about the request. - `StopSequences []string Optional` Sequences that will cause the model to stop generating. Our models stop on `" Human:"`, and may include additional built-in stop sequences in the future. By providing the stop_sequences parameter, you may include additional strings that will cause the model to stop generating. - `WorkspaceID param.Opt[string] Optional` (header parameter) Optional header to select the Workspace for this request. The value is a Workspace ID (for example, `wrkspc_011CZkZaBF1tNoB5wlCeusgy`). Only needed for credentials that can act on more than one Workspace. A credential that belongs to a specific Workspace may omit it; if sent, it must match that Workspace. - `Temperature param.Opt[float64] Optional` **Deprecated**: Deprecated. Models released after Claude Opus 4.6 do not support setting temperature. A value of 1.0 will be accepted for backwards compatibility, all other values will be rejected with a 400 error. Amount of randomness injected into the response. Defaults to `1.0`. Ranges from `0.0` to `1.0`. Use `temperature` closer to `0.0` for analytical / multiple choice, and closer to `1.0` for creative and generative tasks. Note that even with `temperature` of `0.0`, the results will not be fully deterministic. minimum: 0, maximum: 1 - `TopK param.Opt[int64] Optional` **Deprecated**: Deprecated. Models released after Claude Opus 4.6 do not accept top_k; any value will be rejected with a 400 error. Only sample from the top K options for each subsequent token. Used to remove "long tail" low probability responses. [Learn more technical details here](https://towardsdatascience.com/how-to-sample-from-language-models-682bceb97277). Recommended for advanced use cases only. minimum: 0 - `TopP param.Opt[float64] Optional` **Deprecated**: Deprecated. Models released after Claude Opus 4.6 do not support setting top_p. A value >= 0.99 will be accepted for backwards compatibility, all other values will be rejected with a 400 error. Use nucleus sampling. In nucleus sampling, we compute the cumulative distribution over all the options for each subsequent token in decreasing probability order and cut it off once it reaches a particular probability specified by `top_p`. Recommended for advanced use cases only. minimum: 0, maximum: 1 - `Betas []AnthropicBeta Optional` (header parameter) **Deprecated**: Deprecated. This parameter has no effect on this method and will be removed in a future release. Optional header to specify the beta version(s) you want to use. - `const AnthropicBetaMessageBatches2024_09_24 AnthropicBeta = "message-batches-2024-09-24"` - `const AnthropicBetaPromptCaching2024_07_31 AnthropicBeta = "prompt-caching-2024-07-31"` - `const AnthropicBetaComputerUse2024_10_22 AnthropicBeta = "computer-use-2024-10-22"` - `const AnthropicBetaComputerUse2025_01_24 AnthropicBeta = "computer-use-2025-01-24"` - `const AnthropicBetaPDFs2024_09_25 AnthropicBeta = "pdfs-2024-09-25"` - `const AnthropicBetaTokenCounting2024_11_01 AnthropicBeta = "token-counting-2024-11-01"` - `const AnthropicBetaTokenEfficientTools2025_02_19 AnthropicBeta = "token-efficient-tools-2025-02-19"` - `const AnthropicBetaOutput128k2025_02_19 AnthropicBeta = "output-128k-2025-02-19"` - `const AnthropicBetaFilesAPI2025_04_14 AnthropicBeta = "files-api-2025-04-14"` - `const AnthropicBetaMCPClient2025_04_04 AnthropicBeta = "mcp-client-2025-04-04"` - `const AnthropicBetaMCPClient2025_11_20 AnthropicBeta = "mcp-client-2025-11-20"` - `const AnthropicBetaDevFullThinking2025_05_14 AnthropicBeta = "dev-full-thinking-2025-05-14"` - `const AnthropicBetaInterleavedThinking2025_05_14 AnthropicBeta = "interleaved-thinking-2025-05-14"` - `const AnthropicBetaCodeExecution2025_05_22 AnthropicBeta = "code-execution-2025-05-22"` - `const AnthropicBetaExtendedCacheTTL2025_04_11 AnthropicBeta = "extended-cache-ttl-2025-04-11"` - `const AnthropicBetaContext1m2025_08_07 AnthropicBeta = "context-1m-2025-08-07"` - `const AnthropicBetaContextManagement2025_06_27 AnthropicBeta = "context-management-2025-06-27"` - `const AnthropicBetaModelContextWindowExceeded2025_08_26 AnthropicBeta = "model-context-window-exceeded-2025-08-26"` - `const AnthropicBetaSkills2025_10_02 AnthropicBeta = "skills-2025-10-02"` - `const AnthropicBetaFastMode2026_02_01 AnthropicBeta = "fast-mode-2026-02-01"` - `const AnthropicBetaOutput300k2026_03_24 AnthropicBeta = "output-300k-2026-03-24"` - `const AnthropicBetaUserProfiles2026_03_24 AnthropicBeta = "user-profiles-2026-03-24"` - `const AnthropicBetaUserProfiles2026_08_18 AnthropicBeta = "user-profiles-2026-08-18"` - `const AnthropicBetaUserProfiles2026_09_04 AnthropicBeta = "user-profiles-2026-09-04"` - `const AnthropicBetaAdvisorTool2026_03_01 AnthropicBeta = "advisor-tool-2026-03-01"` - `const AnthropicBetaManagedAgents2026_04_01 AnthropicBeta = "managed-agents-2026-04-01"` - `const AnthropicBetaCacheDiagnosis2026_04_07 AnthropicBeta = "cache-diagnosis-2026-04-07"` - `const AnthropicBetaDreaming2026_04_21 AnthropicBeta = "dreaming-2026-04-21"` - `const AnthropicBetaThinkingTokenCount2026_05_13 AnthropicBeta = "thinking-token-count-2026-05-13"` - `const AnthropicBetaServerSideFallback2026_06_01 AnthropicBeta = "server-side-fallback-2026-06-01"` - `const AnthropicBetaServerSideFallback2026_07_01 AnthropicBeta = "server-side-fallback-2026-07-01"` - `const AnthropicBetaFallbackCredit2026_06_01 AnthropicBeta = "fallback-credit-2026-06-01"` - `const AnthropicBetaFallbackCredit2026_07_01 AnthropicBeta = "fallback-credit-2026-07-01"` - `const AnthropicBetaAgentMemory2026_07_22 AnthropicBeta = "agent-memory-2026-07-22"` - `const AnthropicBetaMidConversationToolChanges2026_07_01 AnthropicBeta = "mid-conversation-tool-changes-2026-07-01"` - `const AnthropicBetaCompact2026_01_12 AnthropicBeta = "compact-2026-01-12"` - `const AnthropicBetaComputerUse2025_11_24 AnthropicBeta = "computer-use-2025-11-24"` - `const AnthropicBetaMCPTunnels2026_06_22 AnthropicBeta = "mcp-tunnels-2026-06-22"` - `const AnthropicBetaStructuredOutputs2025_11_13 AnthropicBeta = "structured-outputs-2025-11-13"` - `const AnthropicBetaTaskBudgets2026_03_13 AnthropicBeta = "task-budgets-2026-03-13"` - `const AnthropicBetaThinkingDisplayUpdates2026_08_18 AnthropicBeta = "thinking-display-updates-2026-08-18"` - `const AnthropicBetaCEUserManagement2026_07_13 AnthropicBeta = "ce-user-management-2026-07-13"` - `const AnthropicBetaMidConversationOutputConfig2026_07_01 AnthropicBeta = "mid-conversation-output-config-2026-07-01"` - `const AnthropicBetaThinkingBindingControls2026_08_01 AnthropicBeta = "thinking-binding-controls-2026-08-01"` - `const AnthropicBetaMidConversationSystemClearAt2026_08_21 AnthropicBeta = "mid-conversation-system-clear-at-2026-08-21"` - `const AnthropicBetaCompact2026_09_04 AnthropicBeta = "compact-2026-09-04"` - `const AnthropicBetaInlineTools2026_09_15 AnthropicBeta = "inline-tools-2026-09-15"` - `const AnthropicBetaMCPClient2026_09_15 AnthropicBeta = "mcp-client-2026-09-15"` - `const AnthropicBetaCEPlugins2026_09_01 AnthropicBeta = "ce-plugins-2026-09-01"` - `const AnthropicBetaSpendLimitReads2026_09_26 AnthropicBeta = "spend-limit-reads-2026-09-26"` - `const AnthropicBetaTelemetryDestinations2026_08_11 AnthropicBeta = "telemetry-destinations-2026-08-11"` ## Returns - `type Completion` - `Type Completion` Object type. For Text Completions, this is always `"completion"`. default: completion - `ID string` Unique object identifier. The format and length of IDs may change over time. - `Completion string` The resulting completion up to and excluding the stop sequences. - `Model Model` The model that will complete your prompt. See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options. - `const ModelClaudeHaiku5_5 Model = "claude-haiku-5-5"` Fastest model for high-volume, real-time tasks - `const ModelClaudeSonnet5_5 Model = "claude-sonnet-5-5"` Efficient model for coding and agents - `const ModelClaudeFable5_1 Model = "claude-fable-5-1"` Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows - `const ModelClaudeOpus5_5 Model = "claude-opus-5-5"` Powerful intelligence for coding, knowledge work, and long-running agents - `const ModelClaudeMythos5_1 Model = "claude-mythos-5-1"` Our most capable model for cybersecurity and biology research, available through trusted access programs - `const ModelClaudeSonnet5 Model = "claude-sonnet-5"` Efficient model for coding and agents - `const ModelClaudeFable5 Model = "claude-fable-5"` Next generation of intelligence for the hardest knowledge work and coding problems - `const ModelClaudeMythos5 Model = "claude-mythos-5"` Most capable model for cybersecurity and biology research - `const ModelClaudeOpus5 Model = "claude-opus-5"` Powerful intelligence for long-running agents and coding - `const ModelClaudeOpus4_8 Model = "claude-opus-4-8"` Powerful intelligence for long-running agents and coding - `const ModelClaudeOpus4_7 Model = "claude-opus-4-7"` Powerful intelligence for long-running agents and coding - `const ModelClaudeOpus4_6 Model = "claude-opus-4-6"` Powerful intelligence for long-running agents and coding - `const ModelClaudeSonnet4_6 Model = "claude-sonnet-4-6"` Best combination of speed and intelligence - `const ModelClaudeHaiku4_5 Model = "claude-haiku-4-5"` - `const ModelClaudeHaiku4_5_20251001 Model = "claude-haiku-4-5-20251001"` - `const ModelClaudeOpus4_5 Model = "claude-opus-4-5"` Powerful intelligence for long-running agents and coding - `const ModelClaudeOpus4_5_20251101 Model = "claude-opus-4-5-20251101"` Powerful intelligence for long-running agents and coding - `const ModelClaudeMythosPreview Model = "claude-mythos-preview"` **Deprecated**: Will reach end-of-life on June 30, 2026. Please migrate to claude-mythos-5. Visit https://docs.anthropic.com/en/docs/resources/model-deprecations for more information. New class of intelligence, strongest in coding and cybersecurity - `const ModelClaudeSonnet4_5 Model = "claude-sonnet-4-5"` **Deprecated**: Will reach end-of-life on November 30, 2026. Please migrate to claude-sonnet-5-5. Visit https://docs.anthropic.com/en/docs/resources/model-deprecations for more information. High-performance model for agents and coding - `const ModelClaudeSonnet4_5_20250929 Model = "claude-sonnet-4-5-20250929"` **Deprecated**: Will reach end-of-life on November 30, 2026. Please migrate to claude-sonnet-5-5. Visit https://docs.anthropic.com/en/docs/resources/model-deprecations for more information. High-performance model for agents and coding - `StopReason string` The reason that we stopped. This may be one the following values: * `"stop_sequence"`: we reached a stop sequence — either provided by you via the `stop_sequences` parameter, or a stop sequence built into the model * `"max_tokens"`: we exceeded `max_tokens_to_sample` or the model's maximum ## Example ```go package main import ( "context" "fmt" "github.com/anthropics/anthropic-sdk-go" "github.com/anthropics/anthropic-sdk-go/option" ) func main() { client := anthropic.NewClient( option.WithAPIKey("my-anthropic-api-key"), ) completion, err := client.Completions.New(context.TODO(), anthropic.CompletionNewParams{ MaxTokensToSample: 256, Model: anthropic.ModelClaudeHaiku5_5, Prompt: "\n\nHuman: Hello, world!\n\nAssistant:", }) if err != nil { panic(err.Error()) } fmt.Printf("%+v\n", completion.ID) } ``` ### Response (200) ```json { "id": "compl_018CKm6gsux7P8yMcwZbeCPw", "completion": " Hello! My name is Claude.", "model": "claude-2.1", "stop_reason": "stop_sequence", "type": "completion" } ```