Crystal MCP Server

by erahq Your server? Claim it

answering

Crystal is answering right now. Last checked moments ago.

Self-curating memory your AI tools share: provenance, verified citations, and trust tiers.

Uptime history 36 days of history · worst day 96%

36 days agonow

98.9%

Uptime 24h

91 of 92 checks

—

Tools

hidden behind auth

311 ms

Response time

average over 24h

OAuth sign-in

Access

streamable-http

Crystal missed 2 checks this week

Everything else answered, so this is steady rather than shaky. We check every 15 minutes, which is how a one-off gets told apart from the start of a pattern, and how you hear about the next one within the hour instead of from your users.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 0 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add crystal --transport http https://crystal-api-118881845105.us-east5.run.app/mcp

Settings → Connectors → Add custom connector, then paste this address

https://crystal-api-118881845105.us-east5.run.app/mcp

~/.codex/config.toml

[mcp_servers.crystal]
url = "https://crystal-api-118881845105.us-east5.run.app/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "crystal": {
      "url": "https://crystal-api-118881845105.us-east5.run.app/mcp"
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "crystal": {
      "type": "http",
      "url": "https://crystal-api-118881845105.us-east5.run.app/mcp"
    }
  }
}

This endpoint answered with an authorization challenge. The server is running, and it signs you in through your browser: there is no API key to paste.

Endpoints

URL	Transport	State	Latency	Checked
https://crystal-api-118881845105.us-east5.run.app/mcp	streamable-http	sign-in	296 ms	0 min ago

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Crystal — questions

Answers built from our own checks of this server.

Why is there no tool list for Crystal?

The server answered our handshake with an authorization challenge, so it is running — but it will not describe its tools to an anonymous client. To see them you need to connect with your own credentials. We record it as alive, not as broken: 98.9% of checks in the last 24 hours got a reply.

Is Crystal working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 92 checks got a reply (98.9%), average response time 311 ms. The bar chart above shows every period we have measured.

How do I connect Crystal?

Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address. You sign in through your browser once and the client keeps the session: no key to copy, and it refuses anonymous clients.

How do you sign in to Crystal?

No API key is involved. Crystal answers our knock with an OAuth challenge, so you authorise it once in your browser and the client keeps the session. That is also why we see no tool list: it will not describe itself to an anonymous client, and that is the server working as intended, not a fault.

How fast is Crystal?

It answers our handshake in 311 ms on average, which is faster than 46% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.