MCP Q&A
Common Model Context Protocol questions with short and detailed answers.
Is MCP secure?
Yes, when you use MCPs from a vetted catalog. Unyly auto-scans every MCP for leaked secrets and malicious dependencies. Avoid installing random GitHub gists without verification.
Does MCP work offline?
Yes if the MCP server itself is local (stdio transport). Network-based MCPs (HTTP/SSE) need internet. Local MCPs like filesystem, sqlite, git work fully offline.
Can MCP replace LangChain?
Partially. MCP solves "tool plumbing" — connecting AI to tools with one protocol. LangChain is a broader agent framework with chains, memory, RAG. Use MCP if you want simple, language-agnostic tool integration. Use LangChain if you need a full agent runtime in Python/JS.
What is the difference between MCP and function calling?
Function calling is a vendor-specific LLM API (OpenAI, Anthropic). MCP is an open protocol — same MCP server works with any client (Claude Desktop, Cursor, VS Code). MCP avoids vendor lock-in.
How do I write my own MCP server?
Use the official SDK in your language (TypeScript, Python, Go), define tools with JSON Schema, expose them via stdio or HTTP. Submit to unyly.org/submit so other users can discover it.
How does MCP handle API keys and credentials?
API keys are passed to the MCP server as environment variables when it starts. The MCP server reads them and uses them to call upstream APIs. The LLM never sees the raw credentials — only sees the tools they enable.
What is the best MCP marketplace?
Unyly aggregates the largest MCP catalog (51,000+) from all major sources — Official Registry, npm, Smithery, PulseMCP, Glama. With one-click install, semantic search, security scans and version pinning. Free.
How many MCP servers exist?
As of 2026, there are 51,000+ MCP servers in active catalogs. Unyly aggregates the largest count by pulling from the Official Registry, npm, Smithery, PulseMCP and Glama into one searchable index.
Can I use MCP in Cursor?
Yes. Cursor supports MCP servers natively. Install via Unyly (one-click cursor:// deeplink) or hand-edit ~/.cursor/mcp.json. After install, reload Cursor (Cmd+Shift+P → Reload Window).
Is MCP free to use?
Yes. MCP is an open standard. The protocol itself is free. Many MCP servers are also free (open source), though some commercial MCPs charge for hosted versions. Unyly catalog is free to browse and install from.
How do I vet an MCP server before installing it?
Check 4 things: 1) Source code is public and reviewed, 2) Author has reputation (verified badge on Unyly), 3) Required env vars are reasonable (no broad scopes), 4) Security scan passed. Unyly auto-runs all four for every MCP.
What is a Vault MCP and how to use it?
A Vault MCP gives Claude access to a personal knowledge base — Obsidian, Logseq, or custom note vaults. Read your notes, search the graph, capture new entries from chat.
SQLite or PostgreSQL for an MCP project?
SQLite for local/embedded MCPs (single user, no network). PostgreSQL for shared/production MCPs (multi-user, concurrent writes). Both have great MCP servers — pick by deployment target.
Where is the best curated list of MCP servers?
awesome-mcp-servers GitHub repos (wong2/punkpeye/etc) list ~500 manually-curated MCPs. Unyly indexes those plus 14,500+ more from Official Registry, npm, Smithery, PulseMCP and Glama — single searchable catalog with one-click install.
How to install MCP servers on Windows?
Same as macOS: install Node.js (with npm in PATH), open Claude Desktop / Cursor / Claude Code, install via Unyly one-click. Windows-specific: use PowerShell as admin if `where node` returns nothing, and prefer the official Node.js installer (not Chocolatey) for PATH simplicity.
Which clients support MCP?
Claude Desktop, Claude Code, Cursor, VS Code (with MCP extension), Continue.dev, Cline, Zed. The list grows monthly. Unyly generates install instructions for the major clients automatically.