Create a Text Completion - Claude API Reference
Claude Platform Docs

Create a Text Completion

POST/v1/complete

[Legacy] Create a Text Completion.

The Text Completions API is a legacy API. We recommend using the Messages API going forward.

Future models and features will not be compatible with Text Completions. See our migration guide for guidance in migrating from Text Completions to Messages.

Headers
"anthropic-beta": optional array of AnthropicBeta

Optional header to specify the beta version(s) you want to use.

One of the following:
string
"message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 41 more
One of the following:
"message-batches-2024-09-24"
"prompt-caching-2024-07-31"
"computer-use-2024-10-22"
"computer-use-2025-01-24"
"pdfs-2024-09-25"
"token-counting-2024-11-01"
"token-efficient-tools-2025-02-19"
"output-128k-2025-02-19"
"files-api-2025-04-14"
"mcp-client-2025-04-04"
"mcp-client-2025-11-20"
"dev-full-thinking-2025-05-14"
"interleaved-thinking-2025-05-14"
"code-execution-2025-05-22"
"extended-cache-ttl-2025-04-11"
"context-1m-2025-08-07"
"context-management-2025-06-27"
"model-context-window-exceeded-2025-08-26"
"skills-2025-10-02"
"fast-mode-2026-02-01"
"output-300k-2026-03-24"
"user-profiles-2026-03-24"
"user-profiles-2026-08-18"
"advisor-tool-2026-03-01"
"managed-agents-2026-04-01"
"cache-diagnosis-2026-04-07"
"dreaming-2026-04-21"
"thinking-token-count-2026-05-13"
"server-side-fallback-2026-06-01"
"server-side-fallback-2026-07-01"
"fallback-credit-2026-06-01"
"fallback-credit-2026-07-01"
"agent-memory-2026-07-22"
"mid-conversation-tool-changes-2026-07-01"
"compact-2026-01-12"
"computer-use-2025-11-24"
"mcp-tunnels-2026-06-22"
"structured-outputs-2025-11-13"
"task-budgets-2026-03-13"
"thinking-display-updates-2026-08-18"
"ce-user-management-2026-07-13"
"mid-conversation-output-config-2026-07-01"
"thinking-binding-controls-2026-08-01"
"mid-conversation-system-clear-at-2026-08-21"
Body
max_tokens_to_sample: number

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.

minimum1
model: Model

The model that will complete your prompt.

See models for additional details and options.

One of the following:
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 and our guide to prompt design for more details.

minLength1
metadata: optional Metadata { user_id }

An object describing metadata about the request.

user_id: optional string or null

An external identifier for the user who is associated with the request.

This should be a uuid, hash value, or other opaque identifier. Anthropic may use this id to help detect abuse. Do not include any identifying information such as name, email address, or phone number.

maxLength512
stop_sequences: optional array of string

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.

stream: optional boolean

Whether to incrementally stream the response using server-sent events.

See streaming for details.

temperature: optional number⁠Deprecated

Amount of randomness injected into the response.

Deprecated. Models released after Claude Opus 4.6 do not support setting temperature. A value of 1.0 of will be accepted for backwards compatibility, all other values will be rejected with a 400 error.

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.

maximum1
minimum0
top_k: optional number⁠Deprecated

Only sample from the top K options for each subsequent token.

Deprecated. Models released after Claude Opus 4.6 do not accept top_k; any value will be rejected with a 400 error.

Used to remove "long tail" low probability responses. Learn more technical details here.

Recommended for advanced use cases only.

minimum0
top_p: optional number⁠Deprecated

Use nucleus sampling.

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.

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.

maximum1
minimum0
Returns
Completion object{ id, completion, model, 2 more }
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 for additional details and options.

One of the following:
stop_reason: string or null

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
type: "completion"

Object type.

For Text Completions, this is always "completion".

defaultcompletion
Create a Text Completion
curl https://api.anthropic.com/v1/complete \
    -H 'Content-Type: application/json' \
    -H 'anthropic-version: 2023-06-01' \
    -H "X-Api-Key: $ANTHROPIC_API_KEY" \
    --max-time 600 \
    -d '{
          "max_tokens_to_sample": 256,
          "model": "claude-2.1",
          "prompt": "\n\nHuman: Hello, world!\n\nAssistant:",
          "temperature": 1,
          "top_k": 5,
          "top_p": 0.7
        }'
Returns Examples
Response 200
{
  "id": "compl_018CKm6gsux7P8yMcwZbeCPw",
  "completion": " Hello! My name is Claude.",
  "model": "claude-2.1",
  "stop_reason": "stop_sequence",
  "type": "completion"
}