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AnthropicFastUltra

Claude Sonnet 5

Anthropic's newest Sonnet model, tuned for the best balance of speed, cost, and intelligence. Features a 1M-token context window, 64K max output tokens, and knowledge cutoff to August 2025. Supports adaptive thinking that reasons only when a turn needs it, vision, and tool use. Compatible with the Anthropic Messages and OpenAI Chat Completions formats.

5,574/27,870credits
input / output ยท per 1M tokens
Balanced speed, cost, and intelligence
1M token context window
64K max output tokens
Knowledge cutoff: August 2025
Adaptive thinking (effort-controlled)
Vision and tool use
Streaming support

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Model Specifications

Context Window
1M
tokens
Max Output
64K
tokens
Training Cutoff
2025-08
Compatible SDK
Anthropic, OpenAI

Capabilities

Vision
Function Calling
Streaming
JSON Mode
System Prompt

Token Pricing (per 1M tokens)

Token TypeCreditsUSD Equivalent
Input Tokens5,574$3.72
Output Tokens27,870$18.58
Cached Tokens557$0.37

* 1,500 credits โ‰ˆ $1 (actual charges may vary based on usage)

Quick Start

curl -X POST "https://api.core.today/llm/anthropic/v1/messages" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer cdt_your_api_key" \
  -d '{
  "model": "claude-sonnet-5",
  "messages": [
    {
      "role": "system",
      "content": "You are a research analyst. Provide structured, source-aware analysis."
    },
    {
      "role": "user",
      "content": "Summarize the key findings and open questions from this 200-page technical report and flag any inconsistencies."
    }
  ],
  "max_tokens": 6000
}'

Parameters

ParameterTypeRequiredDefaultDescription
messagesarrayYes-Array of message objects (OpenAI format)
max_tokensintegerNo4096Maximum tokens in response (up to 64000)
streambooleanNofalseEnable Server-Sent Events streaming

Examples

High-throughput Analysis

Fast, cost-efficient analysis over large documents with Claude Sonnet 5

curl -X POST "https://api.core.today/llm/anthropic/v1/messages" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer cdt_your_api_key" \
  -d '{
  "model": "claude-sonnet-5",
  "messages": [
    {
      "role": "system",
      "content": "You are a research analyst. Provide structured, source-aware analysis."
    },
    {
      "role": "user",
      "content": "Summarize the key findings and open questions from this 200-page technical report and flag any inconsistencies."
    }
  ],
  "max_tokens": 6000
}'

Production Code Generation

Generate production-ready code with a strong quality-to-cost ratio

curl -X POST "https://api.core.today/llm/anthropic/v1/messages" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer cdt_your_api_key" \
  -d '{
  "model": "claude-sonnet-5",
  "messages": [
    {
      "role": "system",
      "content": "You are a senior software engineer. Write clean, well-tested, production code."
    },
    {
      "role": "user",
      "content": "Implement a token-bucket rate limiter in TypeScript backed by Redis, with unit tests."
    }
  ],
  "max_tokens": 6000
}'

Tips & Best Practices

1Best default Anthropic model when you want strong reasoning at Sonnet-tier speed and cost
21M context window handles very large codebases and document sets in a single request
364K output enables long-form drafts in a single response
4Sampling params (`temperature`, `top_p`, `top_k`) are unsupported โ€” omit them; a non-default value returns a 400
5Thinking is adaptive-only: use `thinking: {type: "adaptive"}` and control depth with the `effort` parameter; fixed `budget_tokens` returns a 400
6Streaming recommended for long responses
7Compatible with both Anthropic Messages and OpenAI SDK formats

Use Cases

High-volume production workloads
Long-context document understanding (up to 1M tokens)
Code generation and review
Multi-step agentic workflows
Cost-sensitive reasoning tasks