If you searched for an MCP server six months ago, you scrolled through GitHub repos and hoped for the best. That doesn’t work anymore. There are thousands of servers now, spread across categories you didn’t know existed a year ago. The real question is where to look.
Three directories handle most of the traffic: Smithery, AgentNDX, and mcp.so. They overlap in coverage but differ in what they’re actually trying to do.
Smithery
Smithery is a hosted registry built around convenience. You browse servers by category, pick one, and get a config snippet you can paste into Claude Desktop, Cursor, or whatever MCP client you’re running. It tracks download counts and lets the community submit servers with light quality filtering.
The install experience is the best part. If you just want something running in your client without reading docs, Smithery gets you there fast. The tradeoff is depth — metadata is limited to name, description, and popularity. No health monitoring, no auth type filtering, no way to tell if a server was last updated two years ago. It also skews toward hosted and remote servers, so local-first tooling has thinner coverage.
AgentNDX
AgentNDX started from a different premise. Instead of optimizing for one-click installs, we built a structured index that both developers and agents can query. The directory tracks over 25,000 servers with metadata that actually matters for production decisions: auth type, transport protocol, install commands, maintenance status.
A few things set it apart:
- Health monitoring checks whether listed servers are maintained and functional — not just listed
- The skills directory covers agent capabilities beyond MCP, so you can browse servers and skills in one place
- Category filtering goes deeper than name and description. You can narrow by auth type, transport, or specific integration patterns
- Batch curation runs regularly, adding new servers every few days with structured metadata attached
The install experience is more manual than Smithery — you get commands, not one-click buttons. And because curation runs in batches, a brand-new server might take a couple days to show up. But if you’re building an agent that needs to discover servers at runtime, or you want to know whether a server actually works before you wire it into your stack, that’s what the index is designed for.
mcp.so
mcp.so takes the widest-net approach. It scrapes GitHub for anything that looks like an MCP server and drops it into a searchable list. Coverage is broad — around 5,000 servers — and new public repos get indexed quickly.
That breadth comes with noise. A lot of what’s listed is experimental, forked, or abandoned. Metadata is sparse: usually just a name and a GitHub link. There’s no structured data for agents to consume, no health checks, no way to filter by auth or transport. It’s a discovery tool, not a decision tool. Useful when you’re exploring what exists in a space, less useful when you need to pick something reliable.
Side by side
| Smithery | AgentNDX | mcp.so | |
|---|---|---|---|
| Servers indexed | ~2,000 | 25,000+ | ~5,000 |
| How it curates | Community + review | Batch curation + structured metadata | Automated GitHub scraping |
| Install experience | One-click config snippets | Install commands | GitHub links |
| Health monitoring | No | Yes | No |
| Skills directory | No | Yes | No |
| Agent-queryable API | Limited | Yes | No |
| Auth/transport metadata | Partial | Yes | No |
Picking the right one
If speed-to-install is all that matters, start with Smithery. Paste the config, move on.
If you need to filter by auth type, check maintenance status, or build agents that find servers programmatically — that’s AgentNDX. It’s also where you’ll find agent skills alongside servers.
If you’re doing broad research and want to see every public repo that might be an MCP server, mcp.so covers the long tail.
Most people end up checking more than one. They aren’t mutually exclusive. But the gaps between them show up fast once you need structured metadata or reliability signals for a production workflow.
FAQ
Can I submit my server to all three? Yes. Smithery takes community submissions. AgentNDX picks up servers through batch curation and also accepts direct submissions. mcp.so scrapes GitHub, so if your repo is public, it’s probably already there.
Which updates fastest? mcp.so, since it scrapes continuously. AgentNDX adds new servers every few days through curation batches. Smithery updates as submissions come in and get reviewed.
Do any of them verify that servers actually work? AgentNDX runs health monitoring. The other two list servers without ongoing verification.
I’m building an agent that needs to discover MCP servers at runtime. Which one? AgentNDX. The structured metadata and API were built for agent consumption, not just human browsing.