Can the Claude Sonnet 5 API handle long-context coding agents?

Yes. Claude Sonnet 5 API supports a 1M-token context window, and Anthropic reports 85.2% on SWE-bench Verified, 63.2% on SWE-bench Pro, and 80.4% on Terminal-Bench 2.1, making it a strong fit for repository-scale coding agents.

How large is the Claude Sonnet 5 API context window and maximum output?

Claude Sonnet 5 API supports a 1M-token context window by default and up to 128k output tokens on the synchronous Messages API. Anthropic notes that its new tokenizer produces about 30% more tokens for the same text than Claude Sonnet 4.6, so migrations should recount prompts.

When should I choose Claude Sonnet 5 API instead of Claude Opus 4.8?

Choose Claude Sonnet 5 API when you need strong coding, agentic search, computer-use, and document-reasoning performance in the faster Sonnet tier. Choose Claude Opus 4.8 for the hardest reasoning and high-autonomy tasks where peak capability matters more than using a Sonnet-class model.

What changes matter when migrating from Claude Sonnet 4.6 API to Claude Sonnet 5 API?

Claude Sonnet 5 API turns adaptive thinking on by default, removes manual extended thinking budgets, and rejects non-default `temperature`, `top_p`, or `top_k` settings with a 400 error. Tool definitions and response shapes are otherwise designed to stay close to Sonnet 4.6.

How do I call the Claude Sonnet 5 API through CometAPI?

Use CometAPI's native Anthropic Messages endpoint at `POST /v1/messages` with `model` set to `claude-sonnet-5`. Set the Anthropic SDK `base_url` to `https://api.cometapi.com` and authenticate with your CometAPI key.

Is the Claude Sonnet 5 API suitable for enterprise document and knowledge-work automation?

Yes. Anthropic reports Claude Sonnet 5 at 81.6% with tools on GDP.pdf, 73.3% on OfficeQA, and ELO 1618 on GDPval-AA v2, indicating strong performance on professional document reasoning and agentic knowledge work.

Anthropic

Live API Popular

claude-sonnet-5

Claude Sonnet 5 API

Claude Sonnet 5 API is live on CometAPI at $1.6 per million input tokens and $8 per million output tokens, 20 percent below Anthropic list price. One key gives you Claude Sonnet 5 plus 500+ models from OpenAI, Google, and ByteDance under all in one pricing and a single invoice. No seat fees. No monthly minimum. Pay only for what you use. Start free and make your first call in under five minutes.

Starting price

$1.60 / 1M input tokens

Usage-based billing

API health

Operational

99.3% uptime / 24h

Response

19315 ms

Observed API response

Released

Jun 30, 2026

Anthropic

Playground

Try Claude Sonnet 5 with a real request, review its parameters and validate the output before integrating the API.

Overview

A practical overview of Claude Sonnet 5, including important behavior and integration considerations.

Claude Sonnet 5 API Overview

Claude Sonnet 5 API is Anthropic's newest Sonnet-class model for coding agents, tool-using workflows, long-context document reasoning, and everyday professional work. On CometAPI, the model ID is claude-sonnet-5, exposed through both the native Anthropic Messages endpoint and an OpenAI-compatible chat endpoint, so developers can choose between Claude-specific controls and a portable multi-model integration layer.

Technical Specifications

Item	Specification
Model name	Claude Sonnet 5
API model ID	claude-sonnet-5
Provider	Anthropic
CometAPI provider code	anthropic
Input types	Text and image input; PDF/document input is listed in CometAPI catalog features
Output type	Text
Context window	1M tokens, default and maximum on Claude Sonnet 5
Maximum output tokens	128k tokens on the synchronous Messages API
Adaptive thinking	Yes; on by default
Extended thinking	Manual thinking: {type: "enabled", budget_tokens: N} is removed and returns a 400 error
Effort control	Supported through the effort parameter; Anthropic notes the API and Claude Code default to high effort
Sampling parameters	Non-default temperature, top_p, or top_k return a 400 error
Reliable knowledge cutoff	January 2026
Training data cutoff	January 2026

What Is Claude Sonnet 5?

Claude Sonnet 5 is Anthropic's next-generation Sonnet model and a direct upgrade from Claude Sonnet 4.6. Claude Sonnet 5 API is Anthropic's newest Sonnet-class model for coding agents, tool-using workflows, long-context document reasoning, and everyday professional work.

The model narrows the capability gap between Sonnet and Opus. Anthropic's launch notes state that Sonnet 5 is close to Claude Opus 4.8 on agentic performance while retaining the Sonnet class's faster, more efficient role. It is designed for developers who need stronger follow-through than Sonnet 4.6 without moving every workflow to an Opus-tier model.

For API users, Sonnet 5 also changes how generation is controlled. Adaptive thinking is enabled by default, manual extended thinking budgets are no longer accepted, and non-default sampling parameters are rejected. Production migrations from Sonnet 4.6 should therefore retest token budgets, remove manual thinking budgets, and avoid temperature/top-p/top-k overrides.

Features and Highlights of Claude Sonnet 5

1. Stronger Agentic Coding and Terminal Work

Anthropic positions Claude Sonnet 5 as its most agentic Sonnet model yet. In the system card, Claude Sonnet 5 reaches 85.2% on SWE-bench Verified, 63.2% on SWE-bench Pro, 78.3% on SWE-bench Multilingual, and 80.4% on Terminal-Bench 2.1. These results make the Claude Sonnet 5 API well suited to code review, bug investigation, migration planning, test generation, and autonomous engineering agents.

2. 1M-Token Long-Context Reasoning

Claude Sonnet 5 supports a 1M-token context window by default. Anthropic notes that the model uses a new tokenizer that produces approximately 30% more tokens for the same text than Claude Sonnet 4.6, so developers should recount prompts and revisit max_tokens settings when migrating. The large context window is still a major advantage for repository-scale tasks, policy review, financial workbooks, multi-document research, and long customer-support histories.

3. Multimodal Document and Computer-Use Capability

Anthropic's current Claude model overview states that current Claude models support text and image input with text output, multilingual capabilities, and vision.Sonnet 5 scores 67.5% without tools and 81.6% with tools on GDP.pdf, 81.2% on OSWorld-Verified, and 86.7% with tools on ChartMuseum, indicating practical strength on dense documents, GUI-style tasks, and chart reasoning.

4. Claude-Specific Controls Through CometAPI

CometAPI exposes Claude Sonnet 5 through /v1/messages for Anthropic-style integrations and /v1/chat/completions for OpenAI-compatible routing. Use the native Messages endpoint when you need Claude-specific features such as adaptive thinking, effort control, prompt caching, server tools, or Anthropic response shapes. Use the OpenAI-compatible endpoint when your app already standardizes around OpenAI-style chat calls and you want to compare Claude Sonnet 5 against GPT, Gemini, or other CometAPI catalog models.

Benchmark Performance

Anthropic's launch materials and Claude Sonnet 5 system card report broad gains over Claude Sonnet 4.6, especially in coding, agentic search, multimodal reasoning, and professional-task performance.

Capability	Benchmark	Claude Sonnet 5 result	Notes
Coding repair	SWE-bench Verified	85.2%	500 verified software-engineering tasks
Harder coding repair	SWE-bench Pro	63.2%	Larger multi-file diffs and harder repository issues
Multilingual coding	SWE-bench Multilingual	78.3%	300 tasks across 9 programming languages
Terminal coding agents	Terminal-Bench 2.1	80.4%	Mean reward over 445 trials
Agentic coding	FrontierCode v1	38.8%	Real pull-request style tasks from Cognition
Cursor production coding tasks	CursorBench	61.2%	Independently measured by Cursor; Sonnet 4.6 scored 49%
Agentic web search	BrowseComp	84.7%	Adaptive thinking at maximum effort with 10M-token limit and context compaction
Computer use	OSWorld-Verified	81.2%	First-attempt success rate, averaged over five runs
Professional PDF reasoning	GDP.pdf	67.5% without tools, 81.6% with tools	Mean criteria pass rate on 100 professional PDF prompts
Chart understanding	ChartMuseum	70.1% without tools, 86.7% with tools	Strong improvement over Sonnet 4.6
Office document reasoning	OfficeQA / OfficeQA Pro	73.3% / 59.4%	Exact-match scores in an agentic harness
Economic work tasks	GDPval-AA v2	ELO 1618	Independent Artificial Analysis evaluation; ranked second behind Claude Fable 5 in the system-card summary

Claude Sonnet 5

Claude Sonnet 5 vs Sonnet 4.6 vs Opus 4.8 vs Claude Fable 5

Model	Same-type role	Best fit	Selection note
Claude Sonnet 5	Fast, high-intelligence Sonnet model for agents and coding	Coding agents, long-context work, document analysis, production automation	Choose when Sonnet 4.6 is not strong enough but an Opus-tier model is not required for every request.
Claude Sonnet 4.6	Previous Sonnet production model	Existing Sonnet workflows, lower migration risk, established prompts	Upgrade to Sonnet 5 for stronger agentic coding and professional-task performance, but retest token budgets and API parameters.
Claude Opus 4.8	More capable Opus-tier model	Complex reasoning, high-autonomy work, hardest long-horizon agent tasks	Use when the task demands higher peak reasoning; Sonnet 5 can match or approach it on some agentic tasks at selected effort levels.
Claude Fable 5	Anthropic's most capable widely released model	Highest capability workloads and demanding long-horizon agentic work	Use as the upper-end benchmark when quality matters more than using the Sonnet class.

How to Use Claude Sonnet 5 API on CometAPI

Log in to cometapi.com. If you are not our user yet, please register first. Sign into your CometAPI console. Get the access credential API key of the interface. Click “Add Token” at the API token in the personal center, get the token key: sk-xxxxx and submit.

Step 1: Use the Native Anthropic Messages Endpoint

Use /v1/messages when you want the closest Claude API behavior through CometAPI. This is the better path for adaptive thinking, effort control, prompt caching, server tools, streaming, and Claude-style response content blocks.

For Claude Sonnet 5, do not send manual extended thinking budgets such as thinking: {"type": "enabled", "budget_tokens": 32000}. Anthropic recommends adaptive thinking and effort control instead.

Step 2: Use the OpenAI-Compatible Endpoint for Portable Routing

Use /v1/chat/completions when your application already uses OpenAI-style chat calls or when you want to compare Claude Sonnet 5 with other CometAPI catalog models behind the same client pattern.

Step 3: Retest Prompts Before Production

When migrating from Claude Sonnet 4.6, recount prompts under the new tokenizer, remove non-default sampling parameters, and review output limits. Sonnet 5 produces more tokens for the same text than Sonnet 4.6, and adaptive thinking tokens share the max_tokens budget with final response text.

Why Use CometAPI for Claude Sonnet 5?

CometAPI gives developers a single model marketplace for Claude Sonnet 5, Claude Opus-class models, GPT-class models, Gemini-class models, and other frontier AI systems. That is useful when teams want one API key, model comparison, staged rollouts, fallback routing, and easier migration between providers.

For Claude Sonnet 5 specifically, CometAPI's value is the dual endpoint strategy. Teams can use the Anthropic Messages endpoint for Claude-native features and use the OpenAI-compatible endpoint for apps that already standardize on chat-completions style requests. This lets engineering teams test the Claude Sonnet 5 API in realistic coding, document, and agent workflows without rebuilding the entire integration layer first.

Recommended CometAPI Use Cases for Claude Sonnet 5

Claude Sonnet 5 is a strong default candidate for:

Coding agents that read repositories, generate patches, and explain changes.
Code review assistants that prioritize bugs and regression risk.
Long-context document analysis across PDFs, policies, contracts, and research packets.
Customer-support investigation workflows that combine tickets, logs, docs, and account history.
Security review and defensive vulnerability triage.
Data-analysis copilots that explain tables, charts, and business metrics.
Agentic research workflows that browse, summarize, compare, and cite sources.
Internal operations assistants that need reliable multi-step execution.

For CometAPI customers, a good starting policy is:

Workload	Recommended model strategy
High-value coding and agent tasks	Default to `claude-sonnet-5` with higher effort
Long document synthesis	Use `claude-sonnet-5` with careful context packing
Simple classification or extraction	Use a cheaper fast model unless quality requires Sonnet 5
Sensitive security tasks	Use Sonnet 5 with logging, intent checks, and policy-aware UX
Legacy Sonnet workflows	Run A/B evals before replacing Sonnet 4.6
Multi-model applications	Use CometAPI routing and fallback logic

What Does Claude Sonnet 5 Actually Cost?

Claude Sonnet 5 uses token-based API pricing.

Pricing	Input Tokens	Output Tokens
Introductory (until Aug. 31, 2026)	$2 / 1M tokens	$10 / 1M tokens
Standard (from Sept. 1, 2026)	$3 / 1M tokens	$15 / 1M tokens

Anthropic also offers discounted rates for prompt caching and batch processing. One important change is that Sonnet 5 uses a new tokenizer, which typically produces around 30% more tokens for the same text than Sonnet 4.6, so real-world costs may be somewhat higher even though the per-token price is unchanged.

Claude Sonnet 5 API Performance on CometAPI

Claude Sonnet 5 is designed to balance speed, reasoning quality, and cost.

Major improvements include:

Stronger coding performance
Better agentic workflows (planning and executing multi-step tasks)
Native support for 1 million token context windows
Up to 128K output tokens
Improved tool use (browser, terminal, APIs)
Adaptive thinking enabled by default

Compared with Sonnet 4.6, Anthropic reports notable gains in:

Software engineering
Complex reasoning
Autonomous task completion
Long-context understanding

The model is intended as a drop-in replacement for Sonnet 4.6 with minimal API changes.

What Developers Build with Claude Sonnet 5

Developers commonly use Claude Sonnet 5 for:

AI Coding Assistants

Code generation
Refactoring
Debugging
Test generation

AI Agents

Browser automation
Research assistants
Customer support agents
Task automation

Enterprise Applications

Knowledge search
Internal documentation assistants
Workflow automation
Business analytics

Content Generation

Technical writing
Marketing copy
Reports
Documentation

Data Processing

Information extraction
Document summarization
Classification
Structured JSON generation

Because Sonnet 5 combines strong reasoning with relatively low API costs, it is well suited for production applications that need both quality and scalability.

FAQ

Pricing

Use the quick estimate above for a single run, then review the full CometAPI and official-price comparison.

First request

—

Estimated CometAPI usage cost

Ten requests

—

Estimated CometAPI usage cost

Fifteen requests

—

Estimated CometAPI usage cost

Pricing for Claude Sonnet 5

Explore competitive pricing for Claude Sonnet 5, designed to fit various budgets and usage needs. Our flexible plans ensure you only pay for what you use, making it easy to scale as your requirements grow. Discover how Claude Sonnet 5 can enhance your projects while keeping costs manageable.

Model	Comet Price (USD / M Tokens)	Official Price (USD / M Tokens)	Discount
claude-sonnet-5	Input:$1.6/M Output:$8/M	Input:$2/M Output:$10/M	-20%

API

Copy a working endpoint and code example, then open the complete API reference when you need every parameter.

One API, production-ready model access

Authenticate once, call the model endpoint and keep the same billing and observability workflow across providers.

POST/v1/messagesPOST/v1/chat/completions

Sample code and API for Claude Sonnet 5

Access comprehensive sample code and API resources for Claude Sonnet 5 to streamline your integration process. Our detailed documentation provides step-by-step guidance, helping you leverage the full potential of Claude Sonnet 5 in your projects.

POST

/v1/messages

POST

/v1/chat/completions

# Get your CometAPI key from https://www.cometapi.com/console/token
# Export it as: export COMETAPI_KEY="your-key-here"
curl -s https://api.cometapi.com/v1/messages \
  --header "Authorization: $COMETAPI_KEY" \
  --header "content-type: application/json" \
  --data \
'{
  "model": "claude-sonnet-5",
  "max_tokens": 1024,
  "messages": [
    {"role": "user", "content": "Hello, Claude"},
    {"role": "assistant", "content": "Hello!"},
    {"role": "user", "content": "Can you describe LLMs to me?"}
  ]
}' | python3 -c "
import json
import sys

data = json.load(sys.stdin)
for block in data.get('content', []):
    if block.get('type') == 'text':
        print(block.get('text', ''))
"

cURL Code Example

# Get your CometAPI key from https://www.cometapi.com/console/token
# Export it as: export COMETAPI_KEY="your-key-here"
curl -s https://api.cometapi.com/v1/messages \
  --header "Authorization: $COMETAPI_KEY" \
  --header "content-type: application/json" \
  --data \
'{
  "model": "claude-sonnet-5",
  "max_tokens": 1024,
  "messages": [
    {"role": "user", "content": "Hello, Claude"},
    {"role": "assistant", "content": "Hello!"},
    {"role": "user", "content": "Can you describe LLMs to me?"}
  ]
}' | python3 -c "
import json
import sys

data = json.load(sys.stdin)
for block in data.get('content', []):
    if block.get('type') == 'text':
        print(block.get('text', ''))
"

Python Code Example

import anthropic
import os

# Get your CometAPI key from https://www.cometapi.com/console/token, and paste it here
COMETAPI_KEY = os.environ.get("COMETAPI_KEY") or "<YOUR_COMETAPI_KEY>"
BASE_URL = "https://api.cometapi.com"

client = anthropic.Anthropic(
    base_url=BASE_URL,
    api_key=COMETAPI_KEY,
)
message = client.messages.create(
    model="claude-sonnet-5",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Hello, Claude"},
        {"role": "assistant", "content": "Hello!"},
        {"role": "user", "content": "Can you describe LLMs to me?"},
    ],
)
for block in message.content:
    if getattr(block, "type", None) == "text":
        print(block.text)

JavaScript Code Example

import Anthropic from "@anthropic-ai/sdk";

// Get your CometAPI key from https://www.cometapi.com/console/token, and paste it here
const api_key = process.env.COMETAPI_KEY || "<YOUR_COMETAPI_KEY>";
const base_url = "https://api.cometapi.com";

const anthropic = new Anthropic({
  apiKey: api_key,
  baseURL: base_url,
});

const message = await anthropic.messages.create({
  model: "claude-sonnet-5",
  max_tokens: 1024,
  messages: [
    { role: "user", content: "Hello, Claude" },
    { role: "assistant", content: "Hello!" },
    { role: "user", content: "Can you describe LLMs to me?" },
  ],
});

for (const block of message.content) {
  if (block.type === "text") {
    console.log(block.text);
  }
}

Capabilities

Scan the model facts that matter before you choose an architecture or estimate production workload.

Supported capabilities

Features returned by the existing model API.

text-to-text

pdf-to-text

image-to-text

Input and output

Inputs

text

Outputs

text

Production profile

Provider: Anthropic
Context: 1M
Commercial use: Supported

Use cases

Use Claude Sonnet 5 for production workflows that match its text capabilities, then compare alternatives before committing to a long-term integration.

Production chat and agent workflows

Coding, analysis and structured generation

High-volume automation through one API

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Uptime

Review live heartbeat data, endpoint availability and observed response times before moving into production.

Uptime

Request success rate over the last 30 days, reflecting the reliability of each model provider. CometAPI monitors all connected providers in real time, 24/7.

RespondLIVE

19315msAvg. Response

UptimeLIVE

99.3%Avg. Uptime

Versions

Review available model identifiers before pinning a production integration.

claude-sonnet-5

Keep exploring

Compare models and continue your research

Anthropic

Live API Popular

claude-sonnet-5

Claude Sonnet 5 API

Starting price

$1.60 / 1M input tokens

Usage-based billing

API health

Operational

99.3% uptime / 24h

Response

19315 ms

Observed API response

Released

Jun 30, 2026

Anthropic

Playground

Try Claude Sonnet 5 with a real request, review its parameters and validate the output before integrating the API.

Overview

A practical overview of Claude Sonnet 5, including important behavior and integration considerations.

Claude Sonnet 5 API Overview

Technical Specifications

Item	Specification
Model name	Claude Sonnet 5
API model ID	claude-sonnet-5
Provider	Anthropic
CometAPI provider code	anthropic
Input types	Text and image input; PDF/document input is listed in CometAPI catalog features
Output type	Text
Context window	1M tokens, default and maximum on Claude Sonnet 5
Maximum output tokens	128k tokens on the synchronous Messages API
Adaptive thinking	Yes; on by default
Extended thinking	Manual thinking: {type: "enabled", budget_tokens: N} is removed and returns a 400 error
Effort control	Supported through the effort parameter; Anthropic notes the API and Claude Code default to high effort
Sampling parameters	Non-default temperature, top_p, or top_k return a 400 error
Reliable knowledge cutoff	January 2026
Training data cutoff	January 2026

What Is Claude Sonnet 5?

Features and Highlights of Claude Sonnet 5

1. Stronger Agentic Coding and Terminal Work

2. 1M-Token Long-Context Reasoning

3. Multimodal Document and Computer-Use Capability

4. Claude-Specific Controls Through CometAPI

Benchmark Performance

Anthropic's launch materials and Claude Sonnet 5 system card report broad gains over Claude Sonnet 4.6, especially in coding, agentic search, multimodal reasoning, and professional-task performance.

Capability	Benchmark	Claude Sonnet 5 result	Notes
Coding repair	SWE-bench Verified	85.2%	500 verified software-engineering tasks
Harder coding repair	SWE-bench Pro	63.2%	Larger multi-file diffs and harder repository issues
Multilingual coding	SWE-bench Multilingual	78.3%	300 tasks across 9 programming languages
Terminal coding agents	Terminal-Bench 2.1	80.4%	Mean reward over 445 trials
Agentic coding	FrontierCode v1	38.8%	Real pull-request style tasks from Cognition
Cursor production coding tasks	CursorBench	61.2%	Independently measured by Cursor; Sonnet 4.6 scored 49%
Agentic web search	BrowseComp	84.7%	Adaptive thinking at maximum effort with 10M-token limit and context compaction
Computer use	OSWorld-Verified	81.2%	First-attempt success rate, averaged over five runs
Professional PDF reasoning	GDP.pdf	67.5% without tools, 81.6% with tools	Mean criteria pass rate on 100 professional PDF prompts
Chart understanding	ChartMuseum	70.1% without tools, 86.7% with tools	Strong improvement over Sonnet 4.6
Office document reasoning	OfficeQA / OfficeQA Pro	73.3% / 59.4%	Exact-match scores in an agentic harness
Economic work tasks	GDPval-AA v2	ELO 1618	Independent Artificial Analysis evaluation; ranked second behind Claude Fable 5 in the system-card summary

Claude Sonnet 5

Claude Sonnet 5 vs Sonnet 4.6 vs Opus 4.8 vs Claude Fable 5

Model	Same-type role	Best fit	Selection note
Claude Sonnet 5	Fast, high-intelligence Sonnet model for agents and coding	Coding agents, long-context work, document analysis, production automation	Choose when Sonnet 4.6 is not strong enough but an Opus-tier model is not required for every request.
Claude Sonnet 4.6	Previous Sonnet production model	Existing Sonnet workflows, lower migration risk, established prompts	Upgrade to Sonnet 5 for stronger agentic coding and professional-task performance, but retest token budgets and API parameters.
Claude Opus 4.8	More capable Opus-tier model	Complex reasoning, high-autonomy work, hardest long-horizon agent tasks	Use when the task demands higher peak reasoning; Sonnet 5 can match or approach it on some agentic tasks at selected effort levels.
Claude Fable 5	Anthropic's most capable widely released model	Highest capability workloads and demanding long-horizon agentic work	Use as the upper-end benchmark when quality matters more than using the Sonnet class.

How to Use Claude Sonnet 5 API on CometAPI

Step 1: Use the Native Anthropic Messages Endpoint

For Claude Sonnet 5, do not send manual extended thinking budgets such as thinking: {"type": "enabled", "budget_tokens": 32000}. Anthropic recommends adaptive thinking and effort control instead.

Step 2: Use the OpenAI-Compatible Endpoint for Portable Routing

Use /v1/chat/completions when your application already uses OpenAI-style chat calls or when you want to compare Claude Sonnet 5 with other CometAPI catalog models behind the same client pattern.

Step 3: Retest Prompts Before Production

Why Use CometAPI for Claude Sonnet 5?

Recommended CometAPI Use Cases for Claude Sonnet 5

Claude Sonnet 5 is a strong default candidate for:

Coding agents that read repositories, generate patches, and explain changes.
Code review assistants that prioritize bugs and regression risk.
Long-context document analysis across PDFs, policies, contracts, and research packets.
Customer-support investigation workflows that combine tickets, logs, docs, and account history.
Security review and defensive vulnerability triage.
Data-analysis copilots that explain tables, charts, and business metrics.
Agentic research workflows that browse, summarize, compare, and cite sources.
Internal operations assistants that need reliable multi-step execution.

For CometAPI customers, a good starting policy is:

Workload	Recommended model strategy
High-value coding and agent tasks	Default to `claude-sonnet-5` with higher effort
Long document synthesis	Use `claude-sonnet-5` with careful context packing
Simple classification or extraction	Use a cheaper fast model unless quality requires Sonnet 5
Sensitive security tasks	Use Sonnet 5 with logging, intent checks, and policy-aware UX
Legacy Sonnet workflows	Run A/B evals before replacing Sonnet 4.6
Multi-model applications	Use CometAPI routing and fallback logic

What Does Claude Sonnet 5 Actually Cost?

Claude Sonnet 5 uses token-based API pricing.

Pricing	Input Tokens	Output Tokens
Introductory (until Aug. 31, 2026)	$2 / 1M tokens	$10 / 1M tokens
Standard (from Sept. 1, 2026)	$3 / 1M tokens	$15 / 1M tokens

Claude Sonnet 5 API Performance on CometAPI

Claude Sonnet 5 is designed to balance speed, reasoning quality, and cost.

Major improvements include:

Stronger coding performance
Better agentic workflows (planning and executing multi-step tasks)
Native support for 1 million token context windows
Up to 128K output tokens
Improved tool use (browser, terminal, APIs)
Adaptive thinking enabled by default

Compared with Sonnet 4.6, Anthropic reports notable gains in:

Software engineering
Complex reasoning
Autonomous task completion
Long-context understanding

The model is intended as a drop-in replacement for Sonnet 4.6 with minimal API changes.

What Developers Build with Claude Sonnet 5

Developers commonly use Claude Sonnet 5 for:

AI Coding Assistants

Code generation
Refactoring
Debugging
Test generation

AI Agents

Browser automation
Research assistants
Customer support agents
Task automation

Enterprise Applications

Knowledge search
Internal documentation assistants
Workflow automation
Business analytics

Content Generation

Technical writing
Marketing copy
Reports
Documentation

Data Processing

Information extraction
Document summarization
Classification
Structured JSON generation

Because Sonnet 5 combines strong reasoning with relatively low API costs, it is well suited for production applications that need both quality and scalability.

FAQ

Pricing

Use the quick estimate above for a single run, then review the full CometAPI and official-price comparison.

First request

—

Estimated CometAPI usage cost

Ten requests

—

Estimated CometAPI usage cost

Fifteen requests

—

Estimated CometAPI usage cost

Pricing for Claude Sonnet 5

Model	Comet Price (USD / M Tokens)	Official Price (USD / M Tokens)	Discount
claude-sonnet-5	Input:$1.6/M Output:$8/M	Input:$2/M Output:$10/M	-20%

API

Copy a working endpoint and code example, then open the complete API reference when you need every parameter.

One API, production-ready model access

Authenticate once, call the model endpoint and keep the same billing and observability workflow across providers.

POST/v1/messagesPOST/v1/chat/completions

Sample code and API for Claude Sonnet 5

POST

/v1/messages

POST

/v1/chat/completions

# Get your CometAPI key from https://www.cometapi.com/console/token
# Export it as: export COMETAPI_KEY="your-key-here"
curl -s https://api.cometapi.com/v1/messages \
  --header "Authorization: $COMETAPI_KEY" \
  --header "content-type: application/json" \
  --data \
'{
  "model": "claude-sonnet-5",
  "max_tokens": 1024,
  "messages": [
    {"role": "user", "content": "Hello, Claude"},
    {"role": "assistant", "content": "Hello!"},
    {"role": "user", "content": "Can you describe LLMs to me?"}
  ]
}' | python3 -c "
import json
import sys

data = json.load(sys.stdin)
for block in data.get('content', []):
    if block.get('type') == 'text':
        print(block.get('text', ''))
"

cURL Code Example

# Get your CometAPI key from https://www.cometapi.com/console/token
# Export it as: export COMETAPI_KEY="your-key-here"
curl -s https://api.cometapi.com/v1/messages \
  --header "Authorization: $COMETAPI_KEY" \
  --header "content-type: application/json" \
  --data \
'{
  "model": "claude-sonnet-5",
  "max_tokens": 1024,
  "messages": [
    {"role": "user", "content": "Hello, Claude"},
    {"role": "assistant", "content": "Hello!"},
    {"role": "user", "content": "Can you describe LLMs to me?"}
  ]
}' | python3 -c "
import json
import sys

data = json.load(sys.stdin)
for block in data.get('content', []):
    if block.get('type') == 'text':
        print(block.get('text', ''))
"

Python Code Example

import anthropic
import os

# Get your CometAPI key from https://www.cometapi.com/console/token, and paste it here
COMETAPI_KEY = os.environ.get("COMETAPI_KEY") or "<YOUR_COMETAPI_KEY>"
BASE_URL = "https://api.cometapi.com"

client = anthropic.Anthropic(
    base_url=BASE_URL,
    api_key=COMETAPI_KEY,
)
message = client.messages.create(
    model="claude-sonnet-5",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Hello, Claude"},
        {"role": "assistant", "content": "Hello!"},
        {"role": "user", "content": "Can you describe LLMs to me?"},
    ],
)
for block in message.content:
    if getattr(block, "type", None) == "text":
        print(block.text)

JavaScript Code Example

import Anthropic from "@anthropic-ai/sdk";

// Get your CometAPI key from https://www.cometapi.com/console/token, and paste it here
const api_key = process.env.COMETAPI_KEY || "<YOUR_COMETAPI_KEY>";
const base_url = "https://api.cometapi.com";

const anthropic = new Anthropic({
  apiKey: api_key,
  baseURL: base_url,
});

const message = await anthropic.messages.create({
  model: "claude-sonnet-5",
  max_tokens: 1024,
  messages: [
    { role: "user", content: "Hello, Claude" },
    { role: "assistant", content: "Hello!" },
    { role: "user", content: "Can you describe LLMs to me?" },
  ],
});

for (const block of message.content) {
  if (block.type === "text") {
    console.log(block.text);
  }
}

Capabilities

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Supported capabilities

Features returned by the existing model API.

text-to-text

pdf-to-text

image-to-text

Input and output

Inputs

text

Outputs

text

Production profile

Provider: Anthropic
Context: 1M
Commercial use: Supported

Use cases

Use Claude Sonnet 5 for production workflows that match its text capabilities, then compare alternatives before committing to a long-term integration.

Production chat and agent workflows

Coding, analysis and structured generation

High-volume automation through one API

Other models

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Claude Opus 5 is available today. It’s a thoughtful and proactive model that comes close to the frontier intelligence of Claude Fable 5 at half the price.

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OpenAI

GPT 5.6

Start with GPT-5.6 Sol for complex reasoning and coding, choose GPT-5.6 Terra to balance intelligence and cost, or use GPT-5.6 Luna for cost-sensitive, high-volume workloads.

Access to Claude Fable 5 has been restored. It brings 5th-generation intelligence to your most ambitious coding and professional work.

Uptime

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Uptime

Request success rate over the last 30 days, reflecting the reliability of each model provider. CometAPI monitors all connected providers in real time, 24/7.

RespondLIVE

19315msAvg. Response

UptimeLIVE

99.3%Avg. Uptime

Versions

Review available model identifiers before pinning a production integration.

claude-sonnet-5

Keep exploring

Claude Sonnet 5 API

Playground

Overview

Claude Sonnet 5 API Overview

Technical Specifications

What Is Claude Sonnet 5?

Features and Highlights of Claude Sonnet 5

1. Stronger Agentic Coding and Terminal Work

2. 1M-Token Long-Context Reasoning

3. Multimodal Document and Computer-Use Capability

4. Claude-Specific Controls Through CometAPI

Benchmark Performance

Claude Sonnet 5 vs Sonnet 4.6 vs Opus 4.8 vs Claude Fable 5

How to Use Claude Sonnet 5 API on CometAPI

Preparation: Sign Up for API Key

Step 1: Use the Native Anthropic Messages Endpoint

Step 2: Use the OpenAI-Compatible Endpoint for Portable Routing

Step 3: Retest Prompts Before Production

Why Use CometAPI for Claude Sonnet 5?

Recommended CometAPI Use Cases for Claude Sonnet 5

What Does Claude Sonnet 5 Actually Cost?

Claude Sonnet 5 API Performance on CometAPI

What Developers Build with Claude Sonnet 5

AI Coding Assistants

AI Agents

Enterprise Applications

Content Generation

Data Processing

FAQ

Can the Claude Sonnet 5 API handle long-context coding agents?

How large is the Claude Sonnet 5 API context window and maximum output?

When should I choose Claude Sonnet 5 API instead of Claude Opus 4.8?

What changes matter when migrating from Claude Sonnet 4.6 API to Claude Sonnet 5 API?

How do I call the Claude Sonnet 5 API through CometAPI?

Is the Claude Sonnet 5 API suitable for enterprise document and knowledge-work automation?

Pricing

Pricing for Claude Sonnet 5

API

One API, production-ready model access

Sample code and API for Claude Sonnet 5

cURL Code Example

Python Code Example

JavaScript Code Example

Capabilities

Use cases

Other models

Uptime

Uptime

Versions

Compare models and continue your research

Claude Sonnet 5 API

Playground

Overview

Claude Sonnet 5 API Overview

Technical Specifications

What Is Claude Sonnet 5?

Features and Highlights of Claude Sonnet 5

1. Stronger Agentic Coding and Terminal Work

2. 1M-Token Long-Context Reasoning

3. Multimodal Document and Computer-Use Capability

4. Claude-Specific Controls Through CometAPI

Benchmark Performance

Claude Sonnet 5 vs Sonnet 4.6 vs Opus 4.8 vs Claude Fable 5

How to Use Claude Sonnet 5 API on CometAPI

Preparation: Sign Up for API Key

Step 1: Use the Native Anthropic Messages Endpoint

Step 2: Use the OpenAI-Compatible Endpoint for Portable Routing

Step 3: Retest Prompts Before Production

Why Use CometAPI for Claude Sonnet 5?

Recommended CometAPI Use Cases for Claude Sonnet 5

What Does Claude Sonnet 5 Actually Cost?

Claude Sonnet 5 API Performance on CometAPI

What Developers Build with Claude Sonnet 5

AI Coding Assistants

AI Agents

Enterprise Applications

Content Generation

Data Processing

FAQ

Can the Claude Sonnet 5 API handle long-context coding agents?