Heystack vs Spanlens

In-depth architectural comparison of the Heystack and Spanlens MCP servers. Compare execution transports, security boundaries, tool capabilities, quality scores, and ready-to-paste client installation snippets for Claude, Cursor, Windsurf, and VS Code.

Which MCP Server Should You Choose?

H

Choose Heystack when:

• You need dedicated capabilities in the Monitoring domain.
• You prefer local stdio subprocess transport architecture.
• Your security boundary fits: No auth required (Free / Open Source).

Explore Heystack Details

Choose Spanlens when:

• You need dedicated capabilities in the Monitoring domain.
• You prefer local stdio subprocess transport architecture.
• Your security boundary fits: API Key required (Free / Open Source).
• You have access to required keys: SPANLENS_API_KEY.
• Primary tools included: Seven read-only observability tools, Request log queries, Agent trace inspection.

Explore Spanlens Details

Feature & Specification Comparison

Specification	H Heystack Monitoring	Spanlens spanlens Monitoring
Summary	Observability for AI apps: investigate traces, logs, LLM usage, replays and crashes; manage alerts.	Query your Spanlens LLM observability from any MCP client. 7 read tools for request logs, agent traces, cost stats, anomalies, model-savings, and per-user analytics across OpenAI, Anthropic, and Gemini. Open source, self-hostable. npx -y @spanlens/mcp-server
Category & Scope	Monitoring

Tools & Capabilities Breakdown

Ready-to-Paste Client Configurations

Paste either (or both) of these JSON server blocks into your client config file (e.g. claude_desktop_config.json or ~/.cursor/mcp.json).

{
  "mcpServers": {
    "heystack": {
      "command": "npx",
      "args": [
        "-y",
        "heystack"
      ]
    }
  }
}

{
  "mcpServers": {
    "spanlens-spanlens-2": {
      "command": "npx",
      "args": [
        "-y",
        "@spanlens/cli"
      ],
      "env": {
        "SPANLENS_API_KEY": "YOUR_SPANLENS_API_KEY_HERE"
      }
    }
  }
}

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