Spanlens MCP

Name: Spanlens MCP
Author: spanlens

by spanlensversion 0.3.0i★ –iRuns on your computer

Registry nameio.github.spanlens/mcp-server

Install

Overview

Description from the maker (original English)

Query Spanlens LLM observability from Cursor, Claude Desktop, or Continue via MCP.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Search & AI memory
You need to fill in: SPANLENS_API_KEY

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
You fill in yourself: SPANLENS_API_KEY, SPANLENS_BASE_URL

Values marked secret are keys to your account. Never share them or paste them into a chat.

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "spanlens": {
      "command": "npx",
      "args": [
        "-y",
        "@spanlens/mcp-server"
      ],
      "env": {
        "SPANLENS_API_KEY": "your-value",
        "SPANLENS_BASE_URL": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add spanlens --env SPANLENS_API_KEY=your-value --env SPANLENS_BASE_URL=your-value -- npx -y @spanlens/mcp-server

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "spanlens": {
      "command": "npx",
      "args": [
        "-y",
        "@spanlens/mcp-server"
      ],
      "env": {
        "SPANLENS_API_KEY": "your-value",
        "SPANLENS_BASE_URL": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "spanlens": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@spanlens/mcp-server"
      ],
      "env": {
        "SPANLENS_API_KEY": "your-value",
        "SPANLENS_BASE_URL": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

Values you fill in

SPANLENS_API_KEY secret required env
Spanlens API key. Must be a scope=public key (sl_live_pub_*) issued from the Public Keys card at https://spanlens.io/projects — the server refuses to start with a full-access sl_live_* key.
SPANLENS_BASE_URL env
Override the API endpoint for self-hosted Spanlens. Default: https://api.spanlens.io

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 6, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account spanlens, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Search & AI memoryi

More stars than 0% of the other 7243 servers in this category
Published to the registry more recently than 50% of the other 7243 servers in this category
Basic checks equal to or better than 100% of the other 7243 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Spanlens MCP safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

You need to fill in: SPANLENS_API_KEY

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.3.0) reached the registry 39 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Context7, Codebase Memory, Exa

Alternatives

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Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Context7

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Codebase Memory

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Exa

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Connect AI agents to Exa for web search, content fetching, and multi-step research.

Runs in the cloud★ 5,213MITUpdated 44 days ago

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

@spanlens/mcp-server

Query your LLM observability data from inside Cursor, Continue, or Claude Desktop. Powered by Spanlens.

Ask your IDE's agent things like _"what's my OpenAI spend this week?"_, _"any cost anomalies?"_, or _"show me the most expensive trace today"_ — and get real answers from your Spanlens workspace through the Model Context Protocol.

30-second setup

1. Issue a public-scope Spanlens key

Public-scope keys (sl_live_pub_*) are read-only — they can query your dashboard data but cannot trigger LLM proxy spend. This server refuses to start with a full-access key because the credential will live in a plaintext config file in your IDE.

Create one at [spanlens.io/projects](https://spanlens.io/projects) → the Public Keys card at the top → + New public key. Copy the sl_live_pub_… value when it's shown.

2. Add the server to your IDE

Cursor — ~/.cursor/mcp.json (or workspace .cursor/mcp.json )

"mcpServers": { "spanlens": { "command": "npx", "args": ["-y", "@spanlens/mcp-server"], "env": { "SPANLENS_API_KEY": "sl_live_pub_..." } } } }

Claude Desktop — ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows)

"mcpServers": { "spanlens": { "command": "npx", "args": ["-y", "@spanlens/mcp-server"], "env": { "SPANLENS_API_KEY": "sl_live_pub_..." } } } }

Continue — ~/.continue/config.yaml

mcpServers:

name: spanlens command: npx args: ['-y', '@spanlens/mcp-server'] env: SPANLENS_API_KEY: sl_live_pub_...

3. Reload your IDE and start asking

The agent will discover seven tools and use them automatically when relevant.

What you can ask

Question	Tool called
"How much have we spent on LLMs this week?"	`get_stats`
"Break down cost by model for the last 30 days"	`get_stats(groupBy=model)`
"Which provider is costing us the most this week?"	`get_stats(groupBy=provider)`
"Any cost or latency anomalies?"	`get_anomalies`
"Show me the 10 most recent error calls on gpt-4o"	`query_requests`
"List my recent agent runs"	`list_traces`
"Walk me through trace `abc123…`"	`get_trace`
"What models could we swap to save money?"	`get_savings`
"Which end-user is driving the most spend?"	`get_user_analytics`

Available tools

Tool	What it returns
`get_stats`	Aggregate cost, request count, token usage, latency, error rate. Optional `groupBy` for a breakdown of cost, requests, latency and error rate: `model` returns one row per provider and model pair, and `provider` rolls those rows up into one row per provider, with latency and error rate weighted by request count.
`query_requests`	Individual LLM requests with cost, latency, model, error message. Filter by `model`, `provider`, `status`, `userId`, `since`, `limit`.
`list_traces`	Agent trace summaries (name, status, duration, span count, total tokens, total cost) for discovering trace IDs. Filter by `limit`, `status`, `since`, `query`. Pair with `get_trace` for the full span tree.
`get_trace`	Full agent span tree for a trace ID — every LLM/tool/retrieval span with timing, tokens, cost.
`get_anomalies`	Cost / latency / error-rate anomalies the platform has detected. Optional `since` (observation window) and `sigma` (sensitivity).
`get_savings`	Model-swap recommendations with projected monthly savings and adoption status.
`get_user_analytics`	Per-end-user usage breakdown — total cost, request count, models touched, recent calls.

Safety

This server is designed for the IDE-config use case, where the credential sits in a plaintext file that's easy to leak (dotfile sync, screen shares, accidental commits). Two defenses:

Public-scope keys only. The server boots, calls /api/v1/me/key-info against your workspace, and verifies the key has scope=public. If you accidentally paste a full-access sl_live_* key, the server refuses to start with a clear error pointing at the correct key type.
Read-only at the API layer. Even if a public key leaks, it cannot call /proxy/* or /ingest/* — the Spanlens server enforces this with a 403 + PUBLIC_KEY_WRITE_FORBIDDEN code. The blast radius of a leak is "competitor sees my usage stats", not "competitor runs up my OpenAI bill".

Configuration

Environment variable	Default	Notes
`SPANLENS_API_KEY`	_required_	A `sl_live_pub_` key from the Public Keys* card on `/projects`. The server refuses to start without one, and refuses to start with a `sl_live_*` (full) key.
`SPANLENS_BASE_URL`	`https://api.spanlens.io`	Override for self-hosted Spanlens. Trailing slashes are normalised.
`SPANLENS_TIMEOUT_MS`	`30000`	How long each API call may take, in milliseconds, before it fails with a timeout error. Applies to the startup key check and to every tool call. Accepts a whole number from 1 to 600000. Any other value stops the server at startup with an error that names the variable.

Self-hosted Spanlens

"mcpServers": { "spanlens": { "command": "npx", "args": ["-y", "@spanlens/mcp-server"], "env": { "SPANLENS_API_KEY": "sl_live_pub_...", "SPANLENS_BASE_URL": "https://spanlens.your-company.com" } } } }

License

MIT — see LICENSE in the repo root.

Spanlens MCP

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Search & AI memoryi

Common questions

Alternatives

Context7

Codebase Memory

Exa

README from the maker

@spanlens/mcp-server

30-second setup

1. Issue a public-scope Spanlens key

2. Add the server to your IDE

3. Reload your IDE and start asking

What you can ask

Available tools

Safety

Configuration

Self-hosted Spanlens

Links

License