lab · San Francisco · est. 2021
Anthropic
Anthropic publishes the Claude Code harness and the SKILL.md format that became the December 2025 open Agent Skills standard. Managed listings on Harnessmarket carry Anthropic's production SLA and the permission manifest required for enterprise allowlists.
Kind mix
Listings
Advance
Progressive Disclosure Loader
Load the Skill when it is needed. Not 1.2 million of them.
210,000
Harness
Claude Code
The productised coding harness. Tool loop, permissions, Skills, production surfaces.
184,200
Harness
Claude Max
Seat subscription that unlocks the Claude Code loop.
184,000
Skill
CLAUDE.md
Project memory for Claude Code. Not a skill; the file every skill assumes.
92,000
Skill
Frontend Design
Official Anthropic skill. Layout, type, restraint.
47,000
MCP
Claude Desktop MCP
claude_desktop_config.json. The original client surface.
41,000
Skill
Skill Creator
The skill that writes skills. Use it, then delete it.
28,000
Skill
Extract, fill, merge. The boring office loop, portable.
26,000
Skill
XLSX
Excel with formulas that survive a reopen. Not a CSV in a trench coat.
24,000
Advance
Sequential Thinking
Official reasoning scaffold. Use as an advance, not a personality.
22,000
MCP
Claude MCP connectors
Hosted connectors on claude.ai. Prefer vendor servers when both exist.
22,000
Skill
PPTX
Decks as a skill. Not a slide API wrapped in hope.
21,000
Skill
DOCX
Read and write Word trees without the GUI.
19,000
Skill
Security Guidelines
Official secure-coding skill. Secrets, auth, injection.
15,000
Advance
Tool Search
Do not load 200 tools. Search, then load. Context is the budget.
14,000
Harness
Claude Agent SDK
The Claude Code loop as a library. Same harness, your process.
12,000
Skill
MCP Builder
Scaffold an MCP server the harness can actually load.
11,000
Skill
Webapp Testing
Playwright against the app the agent just wrote. Official, not a home-rolled CDP.
9,800
Skill
Brand Guidelines
Load a house style so the agent stops inventing one.
9,000
Skill
Claude API
SDK, auth, and the mistakes that burn tokens. Bundled with Claude Code.
8,600
Advance
Computer Use
Anthropic's desktop loop. The screenshot is the observation.
8,600
Skill
Canvas Design
Poster-grade layout. Not a dashboard.
7,200
Skill
Web Artifacts Builder
React + Tailwind artifacts that are not a single HTML file of regret.
7,200
Skill
Doc Coauthoring
Collaborative writing with a human still on the byline.
4,100
Skill
Internal Comms
Memos, updates, the Friday note. Templates, not a personality.
3,600
Skill
Algorithmic Art
Seeded p5.js. Generative art that can be replayed.
2,800
Skill
Theme Factory
Ten professional palettes so the agent stops inventing lime on navy.
2,400
Skill
Slack GIF Creator
Animated GIFs that fit Slack. Official frivolity.
1,900