When was Claude Opus 4.8 released?

Claude Opus 4.8 was released on May 28, 2026, and is available immediately on claude.ai, the Claude API, Amazon Bedrock, Google Vertex AI, and Microsoft Foundry.

What are the main improvements in Claude Opus 4.8?

Claude Opus 4.8 delivers improvements in agentic tasks, achieves 69.2% on SWE-bench Pro (up from 64.3% on Opus 4.7), is 4x less likely to let code flaws pass unremarked, and has the lowest incorrect-rate across benchmarks (reducing hallucinations).

How is Claude Opus 4.8 priced?

Claude Opus 4.8 is priced the same as Opus 4.5/4.6/4.7—$5 per million input tokens and $25 per million output tokens. Fast mode is now 3x cheaper while delivering 2.5× speed.

What is the effort control feature?

Users on claude.ai now have control over the amount of effort Claude puts into a task. This allows you to balance speed and thoroughness based on your specific needs.

Is Claude Opus 4.8 available for GitHub Copilot?

Yes, Claude Opus 4.8 is generally available for GitHub Copilot as of May 28, 2026.

How does Claude Opus 4.8 reduce hallucinations?

Opus 4.8 achieves lower hallucination rates by abstaining on questions where it's uncertain rather than answering incorrectly. It had the lowest incorrect-rate of all benchmarked models.

Claude Opus 4.8: Agentic Improvements, Faster Speed, and | explainx.ai Blog

TL;DR: Anthropic shipped Claude Opus 4.8 on May 28, 2026, with measurable improvements in agentic tasks, code quality verification, and factual accuracy. Fast mode is now 3x cheaper, effort controls give users fine-grained performance tuning, and it's available across all major platforms today.

Claude Opus 4.8: What's New

Anthropic released Claude Opus 4.8 today (May 28, 2026), describing it as "a modest but tangible improvement" over its predecessor. While the changes may appear incremental, they deliver real impact where it matters most: agentic tasks, code quality, and factual accuracy.

Claude Opus 4.8 is available immediately on:

claude.ai (web interface)
Claude API
Amazon Bedrock
Google Vertex AI
Microsoft Foundry
GitHub Copilot

Key Improvements in Opus 4.8

1. Agentic Task Performance

Claude Opus 4.8 delivers improvements across agentic benchmarks, making it better suited for autonomous coding, debugging, and system-level work.

SWE-bench Pro Results:

Opus 4.8: 69.2%
Opus 4.7: 64.3%
Improvement: +4.9 percentage points

SWE-bench Pro measures the ability to resolve real-world GitHub issues autonomously—a direct test of agentic capabilities.

2. Code Quality Verification

One of the most significant improvements: Claude Opus 4.8 is roughly 4x less likely than Opus 4.7 to allow flaws in code it has written to pass unremarked.

This means:

Better self-correction during code generation
Fewer bugs that slip through unnoticed
Higher confidence in generated code quality
Less manual review required

For teams using Claude for code generation, this translates to tangible time savings and fewer production issues.

3. Lower Hallucination Rate

Claude Opus 4.8 achieved the lowest incorrect-rate of all benchmarked models—the most direct measure of factual hallucination.

How it achieves this:

Abstains on uncertain questions rather than guessing
Prioritizes accuracy over answer coverage
Reduces confidently wrong responses

This makes Opus 4.8 more reliable for critical decisions where wrong answers carry high costs.

Pricing & Performance

Same Pricing, Better Value

Claude Opus 4.8 maintains the same pricing as Opus 4.5/4.6/4.7:

Input: $5 per million tokens
Output: $25 per million tokens

Fast Mode: 3x Cheaper, 2.5x Faster

Fast mode for Opus 4.8 is now 3x cheaper than it was for previous models:

table · 3 cols

Model	Fast Mode Speed	Fast Mode Cost
Opus 4.8	2.5× faster	3× cheaper
Opus 4.7	2.5× faster	Standard fast mode pricing

This makes fast mode viable for more use cases where speed matters but budget is a concern.

New Effort Control Feature

Users on claude.ai now have control over the amount of effort Claude puts into a task.

How It Works:

Adjust effort level based on task complexity
Balance thoroughness vs. speed dynamically
Fine-tune performance for specific use cases

Use Cases:

Low effort: Quick drafts, exploratory coding
Standard effort: Normal development work
High effort: Critical code reviews, complex refactoring
Ultra effort: Architectural decisions, security audits

This pairs perfectly with dynamic workflows (also launched today), which can automatically adjust effort based on subtask requirements.

Dynamic Workflows Integration

Claude Opus 4.8 launches alongside dynamic workflows in Claude Code, enabling:

Orchestration of tens to hundreds of parallel subagents
Autonomous handling of complex, multi-step engineering tasks
Iterative verification and convergence to high-quality outputs

The combination of Opus 4.8's improved agentic performance and dynamic workflows unlocks:

Codebase-wide migrations
Security audits across entire repos
Bug hunts in complex legacy systems
Framework ports spanning thousands of files

Benchmark Comparison: Opus 4.8 vs. Competitors

While Anthropic describes Opus 4.8 as a "modest improvement," the benchmarks tell a compelling story:

Hallucination & Accuracy

Lowest incorrect-rate across all benchmarked models:

Achieves this by abstaining when uncertain
Prioritizes precision over recall
Reduces confidently wrong responses

Code Generation Quality

4× lower flaw pass-through rate compared to Opus 4.7:

Better self-verification during generation
Catches edge cases and logic errors
Reduces manual code review burden

Agentic Capabilities

69.2% on SWE-bench Pro:

Up from 64.3% on Opus 4.7
Measures autonomous issue resolution
Real-world GitHub issues, not synthetic tests

Availability & Integration

Platforms

Claude Opus 4.8 is live on:

claude.ai (web interface)
Claude API (Anthropic)
Amazon Bedrock
Google Vertex AI
Microsoft Foundry
GitHub Copilot

Claude Code

Available in:

Claude Code CLI
Claude Code Desktop
VS Code extension

Works seamlessly with:

Dynamic workflows
Effort controls
Fast mode

When to Use Claude Opus 4.8

Best For:

Agentic coding tasks where autonomous execution matters
Code generation requiring high quality and self-verification
Critical decisions where hallucinations carry high costs
Complex refactoring benefiting from improved reasoning
Security audits requiring thoroughness and accuracy

Also Consider:

Claude Sonnet 4.5 for balanced performance/cost
Claude Haiku for high-volume, low-latency tasks

Effort Control: Practical Examples

Low Effort (Fast Mode)

python

# Quick prototype generation
"Write a basic REST API for user management"

2.5× faster
3× cheaper
Good enough for drafts and exploratory work

Standard Effort

python

# Production code generation
"Implement authentication middleware with JWT validation"

Default performance
Balanced thoroughness
Suitable for most development work

Ultra Effort (with Dynamic Workflows)

python

# Complex migration task
"Create a workflow to migrate our entire codebase from Express to Fastify"

Maximum thoroughness
Parallel subagents
Adversarial verification
Best for critical, complex work

Migration Guide: Opus 4.7 → Opus 4.8

Upgrading is straightforward—Opus 4.8 is API-compatible with Opus 4.7:

API Usage

python

# No changes required
import anthropic

client = anthropic.Anthropic(api_key="your-api-key")

response = client.messages.create(
    model="claude-opus-4.8",  # Update model name
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Your prompt"}
    ]
)

Pricing Impact

Standard mode: No change ($5 input / $25 output)
Fast mode: 3× cheaper (same 2.5× speed)

Expected Improvements

✅ Lower hallucination rate (abstention strategy)
✅ Better code quality verification (4× fewer unnoticed flaws)
✅ Improved agentic performance (+4.9pp on SWE-bench Pro)
✅ Same API, same pricing for standard mode

What the Community Is Saying

Early reactions from developers and researchers highlight the tangible improvements:

"Opus 4.8 is noticeably better at catching its own mistakes. The 4× improvement in code flaw detection is real." — Simon Willison

"The abstention strategy is brilliant—I'd rather have Claude say 'I don't know' than confidently give wrong answers." — Developer feedback

"Fast mode being 3× cheaper is a game-changer for high-volume use cases." — API user

Getting Started with Opus 4.8

Web Interface (claude.ai)

Visit claude.ai
Select Claude Opus 4.8 from the model dropdown
Adjust effort level based on your task
Start chatting

API

python

pip install anthropic

python

import anthropic

client = anthropic.Anthropic(api_key="your-api-key")

response = client.messages.create(
    model="claude-opus-4.8",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Explain the improvements in Opus 4.8"}
    ]
)

print(response.content[0].text)

Claude Code

bash

curl -fsSL https://claude.ai/install.sh | bash

Enable ultracode mode for automatic workflow orchestration.

Sources & Further Reading

This article is based on official announcements and community analysis:

Claude Opus 5 release speculation — Honeycomb leak, July 2026
Grok 4.5 vs Opus 4.7 and 4.8 (July 2026) — how Grok positions against this Opus generation
Dynamic Workflows in Claude Code
Claude Sonnet 4.5 vs Opus 4.8: Which to Use?
Claude API Best Practices 2026

Claude Opus 4.8 is available now on claude.ai, the Claude API, Amazon Bedrock, Vertex AI, Microsoft Foundry, and GitHub Copilot. Pricing remains $5/M input and $25/M output, with fast mode now 3× cheaper.

Claude Opus 4.8: What's New

Claude Opus 4.8 is available immediately on:

claude.ai (web interface)
Claude API
Amazon Bedrock
Google Vertex AI
Microsoft Foundry
GitHub Copilot

Key Improvements in Opus 4.8

1. Agentic Task Performance

Claude Opus 4.8 delivers improvements across agentic benchmarks, making it better suited for autonomous coding, debugging, and system-level work.

SWE-bench Pro Results:

Opus 4.8: 69.2%
Opus 4.7: 64.3%
Improvement: +4.9 percentage points

SWE-bench Pro measures the ability to resolve real-world GitHub issues autonomously—a direct test of agentic capabilities.

2. Code Quality Verification

One of the most significant improvements: Claude Opus 4.8 is roughly 4x less likely than Opus 4.7 to allow flaws in code it has written to pass unremarked.

This means:

Better self-correction during code generation
Fewer bugs that slip through unnoticed
Higher confidence in generated code quality
Less manual review required

For teams using Claude for code generation, this translates to tangible time savings and fewer production issues.

3. Lower Hallucination Rate

Claude Opus 4.8 achieved the lowest incorrect-rate of all benchmarked models—the most direct measure of factual hallucination.

How it achieves this:

Abstains on uncertain questions rather than guessing
Prioritizes accuracy over answer coverage
Reduces confidently wrong responses

This makes Opus 4.8 more reliable for critical decisions where wrong answers carry high costs.

Pricing & Performance

Same Pricing, Better Value

Claude Opus 4.8 maintains the same pricing as Opus 4.5/4.6/4.7:

Input: $5 per million tokens
Output: $25 per million tokens

Fast Mode: 3x Cheaper, 2.5x Faster

Fast mode for Opus 4.8 is now 3x cheaper than it was for previous models:

table · 3 cols

Model	Fast Mode Speed	Fast Mode Cost
Opus 4.8	2.5× faster	3× cheaper
Opus 4.7	2.5× faster	Standard fast mode pricing

This makes fast mode viable for more use cases where speed matters but budget is a concern.

New Effort Control Feature

Users on claude.ai now have control over the amount of effort Claude puts into a task.

How It Works:

Adjust effort level based on task complexity
Balance thoroughness vs. speed dynamically
Fine-tune performance for specific use cases

Use Cases:

Low effort: Quick drafts, exploratory coding
Standard effort: Normal development work
High effort: Critical code reviews, complex refactoring
Ultra effort: Architectural decisions, security audits

This pairs perfectly with dynamic workflows (also launched today), which can automatically adjust effort based on subtask requirements.

Dynamic Workflows Integration

Claude Opus 4.8 launches alongside dynamic workflows in Claude Code, enabling:

Orchestration of tens to hundreds of parallel subagents
Autonomous handling of complex, multi-step engineering tasks
Iterative verification and convergence to high-quality outputs

The combination of Opus 4.8's improved agentic performance and dynamic workflows unlocks:

Codebase-wide migrations
Security audits across entire repos
Bug hunts in complex legacy systems
Framework ports spanning thousands of files

Benchmark Comparison: Opus 4.8 vs. Competitors

While Anthropic describes Opus 4.8 as a "modest improvement," the benchmarks tell a compelling story:

Hallucination & Accuracy

Lowest incorrect-rate across all benchmarked models:

Achieves this by abstaining when uncertain
Prioritizes precision over recall
Reduces confidently wrong responses

Code Generation Quality

4× lower flaw pass-through rate compared to Opus 4.7:

Better self-verification during generation
Catches edge cases and logic errors
Reduces manual code review burden

Agentic Capabilities

69.2% on SWE-bench Pro:

Up from 64.3% on Opus 4.7
Measures autonomous issue resolution
Real-world GitHub issues, not synthetic tests

Availability & Integration

Platforms

Claude Opus 4.8 is live on:

claude.ai (web interface)
Claude API (Anthropic)
Amazon Bedrock
Google Vertex AI
Microsoft Foundry
GitHub Copilot

Claude Code

Available in:

Claude Code CLI
Claude Code Desktop
VS Code extension

Works seamlessly with:

Dynamic workflows
Effort controls
Fast mode

When to Use Claude Opus 4.8

Best For:

Agentic coding tasks where autonomous execution matters
Code generation requiring high quality and self-verification
Critical decisions where hallucinations carry high costs
Complex refactoring benefiting from improved reasoning
Security audits requiring thoroughness and accuracy

Also Consider:

Claude Sonnet 4.5 for balanced performance/cost
Claude Haiku for high-volume, low-latency tasks

Effort Control: Practical Examples

Low Effort (Fast Mode)

python

# Quick prototype generation
"Write a basic REST API for user management"

2.5× faster
3× cheaper
Good enough for drafts and exploratory work

Standard Effort

python

# Production code generation
"Implement authentication middleware with JWT validation"

Default performance
Balanced thoroughness
Suitable for most development work

Ultra Effort (with Dynamic Workflows)

python

# Complex migration task
"Create a workflow to migrate our entire codebase from Express to Fastify"

Maximum thoroughness
Parallel subagents
Adversarial verification
Best for critical, complex work

Migration Guide: Opus 4.7 → Opus 4.8

Upgrading is straightforward—Opus 4.8 is API-compatible with Opus 4.7:

API Usage

python

# No changes required
import anthropic

client = anthropic.Anthropic(api_key="your-api-key")

response = client.messages.create(
    model="claude-opus-4.8",  # Update model name
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Your prompt"}
    ]
)

Pricing Impact

Standard mode: No change ($5 input / $25 output)
Fast mode: 3× cheaper (same 2.5× speed)

Expected Improvements

✅ Lower hallucination rate (abstention strategy)
✅ Better code quality verification (4× fewer unnoticed flaws)
✅ Improved agentic performance (+4.9pp on SWE-bench Pro)
✅ Same API, same pricing for standard mode

What the Community Is Saying

Early reactions from developers and researchers highlight the tangible improvements:

"Opus 4.8 is noticeably better at catching its own mistakes. The 4× improvement in code flaw detection is real." — Simon Willison

"The abstention strategy is brilliant—I'd rather have Claude say 'I don't know' than confidently give wrong answers." — Developer feedback

"Fast mode being 3× cheaper is a game-changer for high-volume use cases." — API user

Getting Started with Opus 4.8

Web Interface (claude.ai)

Visit claude.ai
Select Claude Opus 4.8 from the model dropdown
Adjust effort level based on your task
Start chatting

API

python

pip install anthropic

python

import anthropic

client = anthropic.Anthropic(api_key="your-api-key")

response = client.messages.create(
    model="claude-opus-4.8",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Explain the improvements in Opus 4.8"}
    ]
)

print(response.content[0].text)

Claude Code

bash

curl -fsSL https://claude.ai/install.sh | bash

Enable ultracode mode for automatic workflow orchestration.

Sources & Further Reading

This article is based on official announcements and community analysis:

Claude Opus 5 release speculation — Honeycomb leak, July 2026
Grok 4.5 vs Opus 4.7 and 4.8 (July 2026) — how Grok positions against this Opus generation
Dynamic Workflows in Claude Code
Claude Sonnet 4.5 vs Opus 4.8: Which to Use?
Claude API Best Practices 2026

Claude Opus 4.8: What's New

Key Improvements in Opus 4.8

1. Agentic Task Performance

2. Code Quality Verification

3. Lower Hallucination Rate

Pricing & Performance

Same Pricing, Better Value

Fast Mode: 3x Cheaper, 2.5x Faster

New Effort Control Feature

Dynamic Workflows Integration

Benchmark Comparison: Opus 4.8 vs. Competitors

Hallucination & Accuracy

Code Generation Quality

Agentic Capabilities

Availability & Integration

Platforms

Claude Code

When to Use Claude Opus 4.8

Effort Control: Practical Examples

Low Effort (Fast Mode)

Standard Effort

Ultra Effort (with Dynamic Workflows)

Migration Guide: Opus 4.7 → Opus 4.8

API Usage

Pricing Impact

Expected Improvements

What the Community Is Saying

Getting Started with Opus 4.8

Web Interface (claude.ai)

API

Claude Code

Sources & Further Reading

Related Reading

Claude Opus 4.8: What's New

Key Improvements in Opus 4.8

1. Agentic Task Performance

2. Code Quality Verification

3. Lower Hallucination Rate

Pricing & Performance

Same Pricing, Better Value

Fast Mode: 3x Cheaper, 2.5x Faster

New Effort Control Feature

Dynamic Workflows Integration

Benchmark Comparison: Opus 4.8 vs. Competitors

Hallucination & Accuracy

Code Generation Quality

Agentic Capabilities

Availability & Integration

Platforms

Claude Code

When to Use Claude Opus 4.8

Effort Control: Practical Examples

Low Effort (Fast Mode)

Standard Effort

Ultra Effort (with Dynamic Workflows)

Migration Guide: Opus 4.7 → Opus 4.8

API Usage

Pricing Impact

Expected Improvements

What the Community Is Saying

Getting Started with Opus 4.8

Web Interface (claude.ai)

API

Claude Code

Sources & Further Reading

Related Reading

Related posts

Claude Fable 5 and Mythos 5: SOTA Autonomy and Safeguards

Anthropic: Automated Researchers Can Reliably Mitigate Alignment Failures

Anthropic Insights: External Researchers Study Real Claude Usage Data

Related posts

Claude Fable 5 and Mythos 5: SOTA Autonomy and Safeguards

Anthropic: Automated Researchers Can Reliably Mitigate Alignment Failures

Anthropic Insights: External Researchers Study Real Claude Usage Data