Tools

Self-improving agent from Nous Research with built-in memory and a learning loop that turns experience into skills. Works with any model provider; the hermes command has a terminal UI, and a gateway connects it to Telegram, Slack and more and runs scheduled tasks.

Behavior guidelines drawn from Karpathy's observations of how LLMs go wrong when coding: think before acting, keep it simple, make surgical changes only, and drive work by verifiable goals. Can also be used directly as a CLAUDE.md.

Four guidelines based on Karpathy's observations of common LLM coding mistakes: think before coding, prefer simplicity, make only necessary changes, and work toward verifiable goals. Ships as a plugin skill or works as a CLAUDE.md. Community-made, not by Karpathy.

Open-source terminal coding agent that switches freely between model providers. Includes a build agent that edits code, a read-only plan agent for analysis, subagents, and a desktop app. Formerly sst/opencode.

Guides users through co-writing proposals, technical specs and decision docs in three stages: gather context, refine section by section, then test with a fresh session that lacks the context to catch what readers won't understand. Official Anthropic skill.

Develops a design philosophy first, then draws posters, illustrations and other static visuals in code, exporting PNG or PDF. Emphasizes original work rather than copying existing artists. Official Anthropic skill.

Drives local web apps with Python Playwright scripts to verify features, debug the UI, take screenshots and read browser logs. Includes helper scripts to start and stop dev servers. Official Anthropic skill.

Ten built-in color and font themes to apply to slides, documents, reports and HTML landing pages, or generate a new theme on demand. Official Anthropic skill.

Creates generative art such as flow fields and particle systems with p5.js and seeded randomness: first writes an algorithmic design philosophy, then outputs an interactive HTML viewer with tunable parameters. Official Anthropic skill.

Reference for the Claude API and Anthropic SDK: model selection and pricing, streaming, tool use, prompt caching, Managed Agents and more, plus workflows for model migration and prompt audits. Official Anthropic skill.

Builds multi-component web pages that need state or routing with React, Tailwind CSS and shadcn/ui, using bundled init and build scripts, then packs them into a single HTML file for a claude.ai Artifact. Official Anthropic skill.

Makes GIFs that follow Slack's recommended size, frame rate, color and length for emoji (128x128) and message GIFs (480x480), with animation tips and tools to assemble and validate them. Built on Python and Pillow. Official Anthropic skill.

Guides agents in building quality MCP servers: research the protocol and target API, design tools, implement with Python (FastMCP) or the TypeScript SDK, and write evaluation questions to test the result. Official Anthropic skill.

Creates, edits and analyzes Excel spreadsheets: formulas, formatting, charts and data cleaning, plus conversion between CSV, TSV and other tabular formats. The official Anthropic skill behind Claude's document features; source-available, not open source.

Official Claude Code plugin for the prompts.chat library: search prompts and Agent Skills from your coding assistant, fill in variables and improve prompts with AI. Includes commands, subagents and a remote MCP; saving your own prompts needs an API key.

'Laziest senior engineer' mode: checks whether the work is needed and whether existing code, the standard library or platform features cover it, then writes the minimum code while keeping validation, error handling and security. For Claude Code and Codex; its hook needs Node.js.

Has the agent follow a 'don't write it if you can avoid it' ladder: ask if it's needed, then reuse existing code, the standard library, platform features and installed dependencies, writing only the minimum while keeping validation, error handling, security and accessibility.

Generates hook rules from a one-line description or by analyzing recent conversations. Rules are Markdown files with match conditions that block or warn on dangerous commands and unwanted patterns, and take effect without a restart. Official Anthropic plugin.

A seven-phase feature development workflow: clarify requirements, explore the codebase with parallel subagents, design the architecture, implement, then run a quality review. Start it with /feature-dev. Official Anthropic plugin.

Six specialized review subagents that check comment accuracy, test coverage, silent failures, type design, code style and simplification opportunities. Run them individually or all at once. Official Anthropic plugin.

Git commit commands: /commit writes messages in the repo's style, /commit-push-pr branches, commits, pushes and opens a PR in one step (needs the gh CLI), and /clean_gone removes local branches deleted on the remote. Official Anthropic plugin.

Toolkit for building Claude Code plugins: 7 skills on plugin structure, hooks, MCP integration, commands, subagents and skill writing, a guided eight-phase create command, and subagents for agent generation, plugin validation and skill review. Maintained by Anthropic.

Scaffolds a Claude Agent SDK project in Python or TypeScript interactively with /new-sdk-app, then a verifier agent checks dependencies, config and code against official best practices. Maintained by Anthropic.

Recreates the deprecated Explanatory output style with a SessionStart hook: adds Insight notes before and after code that explain implementation trade-offs and codebase conventions. Official Anthropic plugin; uses extra tokens.