By Momenul Ahmad, Founder and Lead Architect, SEOSiri. Published and last verified: October 21, 2026.
MCP server registries are the app stores of the Model Context Protocol: public directories where developers publish servers and where AI assistants and builders find them. This guide compares the main registries, lists the MCP servers developers install most, shows SEOSiri's own open-source MCP servers, and gives a repeatable way to vet any server before it touches real data.
1. Which MCP registries matter?
Five directories cover most discovery. Each one counts servers differently, so published totals vary a lot. In 2026 comparisons, Glama is reported anywhere from about 21,000 to 37,000 servers, mcp.so from 17,000 to 20,000+, and Smithery from roughly 3,000 to 7,000. Independent census site AgentPopulation publishes its own ranges on its Directories page. Use these numbers for scale, not for exact comparison.
| Registry | Best for | How it works |
|---|---|---|
| Official MCP Registry | Canonical, spec-defined entries | Upstream index that other directories can mirror |
| Glama | Broadest coverage and quality signals | Auto-indexes open-source servers from GitHub; owners can claim listings |
| mcp.so | Community and third-party servers | Open submissions and a playground |
| Smithery | Easy install and hosted servers | CLI for installing and publishing servers |
| PulseMCP | Human-reviewed picks | Curated directory with visitor estimates |
AgentPopulation's Directories page also lists SEOSiri as a source reference on its Glama, mcp.so and Smithery entries. Treat that as a credibility signal about our research, not as a quality rating of any listing.
The global AI agent census dashboard mapping active ecosystem directories, highlighting SEOSiri's official validation across decentralized Model Context Protocol (MCP) data aggregates.
2. Which MCP servers do developers install most?
Current 2026 developer guides keep naming the same servers, and official vendor servers lead because the product's own team maintains them. This is a snapshot of commonly recommended servers, not a popularity ranking.
| Server | What it does | Source |
|---|---|---|
| GitHub MCP | Repositories, issues and pull requests | github/github-mcp-server |
| Playwright MCP | Browser automation and web testing | microsoft/playwright-mcp |
| Context7 | Current library documentation for coding assistants | upstash/context7 |
| Sentry MCP | Errors and performance data for debugging | getsentry/sentry-mcp |
| Notion MCP | Search and edit workspace pages | makenotion/notion-mcp-server |
| Neon MCP | Manage serverless Postgres | neondatabase/mcp-server-neon |
| Reference servers | Filesystem, Fetch, Git and Memory examples | modelcontextprotocol/servers |
Keep your active list short. Every connected server adds permissions you must review and tool definitions your assistant must carry.
3. SEOSiri MCP servers by use case
SEOSiri maintains open-source, local-first MCP servers under the SEOSiri-Official GitHub organization. These five are listed on Glama today, grouped by what they help you do:
| Use case | Server | What it does |
|---|---|---|
| Technical SEO and GEO | seosiri-content-schema-mcp | Generates structured data such as TechArticle JSON-LD for your content |
| Technical SEO and GEO | seosiri-keyword-cluster-mcp | Semantic keyword clustering, search intent classification, cannibalization detection and topical authority mapping |
| Security and infrastructure | seosiri-dns-sec-audit-mcp | DNS record audits, SSL/TLS inspection and HTTP security header analysis |
| Security and infrastructure | seosiri-api-guard-mcp-server | Validates, sanitizes and authorizes LLM-generated API payloads with OWASP, PCI-DSS and HIPAA-style profiles |
| Security and infrastructure | seosiri-db-infra-mcp | Read-only Postgres queries, schema inspection, AWS S3 and Cloudflare audits (architecture guide) |
Beyond these, the SEOSiri ecosystem includes the Industrial AI Gateway, the STAL server (source code), data-pipeline and IoT bridge servers, and an MCP drift detector for schema validation at the edge. The central SEOSiri MCP directory lists them all, and you can try tools live in the SEOSiri Developer Portal.
4. How do you vet an MCP server before connecting it?
Treat every server as code that can read data and act with your credentials. Work through this checklist, which maps to widely used security frameworks:
- Check the source. Read the repository, license, recent commits and open issues. Prefer official vendor servers.
- Use least privilege. Start with read-only keys and the narrowest scopes.
- Treat returned content as untrusted. Web pages and documents can carry hidden instructions aimed at your model. See the OWASP Top 10 for LLM Applications.
- Test before you trust. Inspect the tool list and schemas, then call each tool with bad input.
npx @modelcontextprotocol/inspector - Audit the code and dependencies. Run static analysis, dependency and secret scans with the pipeline in our polyglot code audit guide.
- Record your decision. Align your review with the NIST AI Risk Management Framework or ISO/IEC 42001 so the review is repeatable.
The protocol is defined in the official MCP documentation, first announced by Anthropic in November 2024.
5. How do you publish your own MCP server?
Open-source the code with a clear README, license and tool descriptions, then make it easy to discover:
- Describe each tool in one plain sentence, with constrained inputs and predictable outputs.
- Keep the README specific: what it does, how to install, what permissions it needs.
- Check that Glama has indexed the repository, and claim the listing, because unclaimed servers have limited discoverability.
- Submit to mcp.so and publish to Smithery with its CLI.
- Link back to a documentation page on your own site, as the SEOSiri servers do.
6. Frequently asked questions
What is an MCP server registry?
A registry is a searchable directory of MCP servers with descriptions, install details and source links, so assistants and developers can find and add tools quickly.
Which MCP directory should I use first?
Start with the Official MCP Registry for canonical entries, then use Glama, mcp.so, Smithery and PulseMCP to compare more options.
Are MCP servers in public directories safe?
Not automatically. Most are community projects, so review the code and permissions, use least-privilege credentials, and test before connecting real data.
Why do directories report different server counts?
Each directory indexes differently: some crawl GitHub automatically, others rely on submissions or human review, and totals change daily.
Where can I find SEOSiri's MCP servers?
On Glama under the SEOSiri-Official publisher, on GitHub under SEOSiri-Official, and in the central SEOSiri MCP directory.
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