Catalog / Categories

Agent building

Creating, testing and evaluating skills, agents and MCP servers.

Entries

• Agent Skills specification

  The open SKILL.md format that lets one skill folder work in Claude, ChatGPT, Codex, Gemini CLI, Cursor, GitHub Copilot and dozens of other agents.

  Standard by Agent Skills (originally developed by Anthropic) Claude apps, Claude Code, ChatGPT, Codex, Gemini, Cursor, Any agent

  Official Reviewed — safe to install Guidance only

• Anthropic skills

  Anthropic's own skills for documents, design, art, internal comms and building new skills and MCP servers.

  Plugin by Anthropic Claude apps, Claude Code

  Official Reviewed — install with care Runs on your machine

• OpenAI plugins (Codex official marketplace)

  The built-in plugin catalog for Codex and ChatGPT. It has 62 plugins from OpenAI and partners that bundle skills, app connectors and MCP servers for tools like GitHub, Figma, Notion, Slack, Stripe and Google Drive.

  Plugin by OpenAI Codex, ChatGPT

  Official Reviewed — install with care Changes things freely

• SkillSpector

  NVIDIA's scanner that checks an agent skill or MCP server for prompt injection, data exfiltration and other risks before you install it.

  Tool by NVIDIA Any agent, Claude Code, Codex, Gemini

  Official Reviewed — safe to install Runs on your machine

• AGENTS.md

  A plain Markdown file at the root of a repo that tells any coding agent how to build, test and work in the project.

  Standard by Agentic AI Foundation (Linux Foundation) Codex, Claude Code, Cursor, Gemini, Any agent

  Official Reviewed — safe to install Guidance only

• Cisco Skill Scanner

  Cisco AI Defense's scanner for agent skills, combining YARA and pattern rules, code dataflow analysis and an optional LLM judge to flag prompt injection, exfiltration and malicious code.

  Tool by Cisco AI Defense Any agent, Claude Code, Codex, Cursor

  Official Reviewed — safe to install Runs on your machine

• Claude Agent SDK

  Anthropic's Python and TypeScript libraries for building your own agents on the same loop, tools, permissions and MCP support that run Claude Code.

  Tool by Anthropic Claude Code, Any agent

  Official Reviewed — install with care Changes things freely

• Claude Code official plugin directory

  Anthropic's plugin marketplace for Claude Code, with Anthropic-built plugins for code review, security review, plugin and MCP development, plus vetted partner plugins.

  Plugin by Anthropic Claude Code

  Official Reviewed — install with care Changes things freely

• Claude Opus 5.5

  Anthropic's recommended default model for long-running coding, agent work and document-heavy knowledge work, with a 1M-token context window.

  Model by Anthropic Claude apps, Claude Code, Any agent

  Official Reviewed — safe to install Guidance only

• DeepSeek-V4-Pro

  DeepSeek's open-weight flagship under the MIT license, for teams that need to self-host or want a low-cost hosted API for agent and coding work.

  Model by DeepSeek Any agent

  Official Reviewed — safe to install Guidance only

• Gemini 3.8 Flash

  Google's newest stable Gemini model, built for agents and long software tasks at Flash pricing, with 1M-token multimodal input.

  Model by Google Any agent

  Official Reviewed — safe to install Guidance only

• GPT-6 Astra

  OpenAI's most capable API model, recommended for complex reasoning, coding, computer use, research and document creation.

  Model by OpenAI Any agent

  Official Reviewed — safe to install Guidance only

• MCP Inspector

  The MCP project's official tool for connecting to an MCP server and exercising its tools, resources and prompts, in a web UI, a terminal UI or a scriptable CLI.

  Tool by Model Context Protocol Any agent

  Official Reviewed — install with care Runs on your machine

• MCP reference servers

  The seven reference MCP servers kept by the MCP steering group — filesystem, git, fetch, memory, time, sequential thinking and a test server — as working examples of the protocol.

  MCP server by Model Context Protocol Any agent, Claude apps, Claude Code, Cursor, Codex

  Official Reviewed — install with care Changes things freely

• MCP Registry

  The official public list of MCP servers, with an API clients can query and a CLI for publishing your own server under a verified namespace.

  Tool by Model Context Protocol Any agent

  Official Reviewed — safe to install Reads your accounts

• OpenAI plugins & Apps SDK

  OpenAI's official way to package skills, an MCP server and optional UI into one plugin that people install from a shared ChatGPT and Codex directory.

  Tool by OpenAI ChatGPT, Codex

  Official Reviewed — safe to install Guidance only

• skills CLI (npx skills)

  Installs Agent Skills from GitHub, GitLab, any git URL or a local folder into Claude Code, Codex, Cursor, Gemini CLI and 75+ other agents with one command.

  Tool by Vercel Labs Claude Code, Codex, Cursor, Gemini, Any agent

  Official Reviewed — install with care Runs on your machine

Curated by Andrew Borden-Chisholm. Notes on building with these tools are on the blog.