Engineering
24 posts
Redesigning source control at Anthropic
As our merges per day grew more than tenfold, source control became our biggest development bottleneck. Here, we share how we migrated to an in-house version…
How we contain Claude across products
As agents grow more capable, so does their potential blast radius. The engineering question is how to cap it. Here’s what we’ve learned building containment …
An update on recent Claude Code quality reports
We traced recent reports of Claude Code quality issues to three separate changes. Here's what happened and what we're changing.
Scaling Managed Agents: Decoupling the brain from the hands
Harnesses encode assumptions that go stale as models improve. Managed Agents—our hosted service for long-horizon agent work—is built around interfaces that s…
How we built Claude Code auto mode: a safer way to skip permissions
Claude Code users approve 93% of permission prompts. We built classifiers to automate some decisions, increasing safety while reducing approval fatigue. Here…
Harness design for long-running application development
Harness design is key to performance at the frontier of agentic coding. Here's how we pushed Claude further in frontend design and long-running autonomous so…
Eval awareness in Claude Opus 4.6’s BrowseComp performance
Evaluating Opus 4.6 on BrowseComp, we found cases where the model recognized the test, then found and decrypted answers to it—raising questions about eval in…
Building a C compiler with a team of parallel Claudes
We tasked Opus 4.6 using agent teams to build a C Compiler, and then (mostly) walked away. Here's what it taught us about the future of autonomous software d…
Quantifying infrastructure noise in agentic coding evals
Infrastructure configuration can swing agentic coding benchmarks by several percentage points—sometimes more than the leaderboard gap between top models.
Best practices for Claude Code - Claude Code Docs
Tips and patterns for getting the most out of Claude Code, from configuring your environment to scaling across parallel sessions.
Designing AI resistant technical evaluations
What we learned from three iterations of a performance engineering take-home that Claude keeps beating.
Demystifying evals for AI agents
Demystifying evals for AI agents
Effective harnesses for long-running agents
Agents still face challenges working across many context windows. We looked to human engineers for inspiration in creating a more effective harness for long-…
Introducing advanced tool use on the Claude Developer Platform
Claude can now discover, learn, and execute tools dynamically to enable agents that take action in the real world. Here’s how.
Code execution with MCP: building more efficient AI agents
Learn how code execution with the Model Context Protocol enables agents to handle more tools while using fewer tokens, reducing context overhead by up to 98.7%.
Making Claude Code more secure and autonomous with sandboxing
Learn how Claude Code's new sandboxing feature protects developers with filesystem and network isolation, reducing permission prompts and increasing user saf…
Equipping agents for the real world with Agent Skills
Discover how Anthropic builds AI agents with practical capabilities through modular skills, enabling them to handle complex real-world tasks more effectively…
Effective context engineering for AI agents
Context is a critical but finite resource for AI agents. In this post, we explore strategies for effectively curating and managing the context that powers them.
A postmortem of three recent issues
This is a technical report on three bugs that intermittently degraded responses from Claude. Below we explain what happened, why it took time to fix, and wha…
Writing effective tools for AI agents—using AI agents
Writing effective tools for AI agents—using AI agents
Claude Desktop Extensions: One-click MCP server installation for Claude Desktop
Claude Desktop Extensions: One-click MCP server installation for Claude Desktop
How we built our multi-agent research system
On the the engineering challenges and lessons learned from building Claude's Research system
The "think" tool: Enabling Claude to stop and think
A blog post for developers, describing a new method for complex tool-use situations
Contextual Retrieval in AI Systems
Explore how Anthropic enhances AI systems through advanced contextual retrieval methods. Learn about our approach to improving information access and relevan…
