Connect Claude Desktop to Lawbster¶

In two minutes, Claude Desktop answers questions about German and European law with verified, citable references. Setup: one JSON entry.

Prerequisites¶

Claude Desktop installed (macOS / Windows / Linux)
A Lawbster account → 14 days free (no credit card)
An API key (sk-legal-…) from the portal under Keys

Plain-text token shown only once

When you create the key, the plain text appears exactly once. Copy it straight into the config — otherwise rotate.

Step 1 — Open the config file¶

Platform	Path
macOS	`~/Library/Application Support/Claude/claude_desktop_config.json`
Windows	`%APPDATA%\Claude\claude_desktop_config.json`
Linux	`~/.config/Claude/claude_desktop_config.json`

Create the file with {} if it doesn't exist.

Step 2 — Add the Lawbster entry¶

{
  "mcpServers": {
    "lawbster": {
      "type": "http",
      "url": "https://lawbster.planitprima.com/mcp",
      "headers": {
        "Authorization": "Bearer sk-legal-YOUR-API-KEY"
      }
    }
  }
}

If you already have other MCP servers configured, just add the lawbster block.

Step 3 — Restart Claude Desktop¶

Fully quit Claude Desktop (not just close the window) and reopen. The MCP icon in the input bar now shows Lawbster with eight tools.

Step 4 — Test it¶

Ask Claude:

What are the prerequisites for a non-pecuniary damages claim under § 253 BGB? Please cite sources.

Claude calls legal_search, retrieves the full text of § 253 BGB, returns a citable answer and can — on request — pull related BGH decisions via legal_find_citing_decisions.

Tips for better answers¶

Enable all Lawbster tools in the MCP menu — Claude picks the right tool automatically. Tool descriptions are written so Claude makes the right choice without explicit instructions.

Use the bundled prompts: /legal_research, /citation_resolve, /compare_de_eu show up as slash commands. They force Claude into a clean research workflow with mandatory tool use and a ban on invented citations.

Ask follow-ups. Lawbster gives more than hits — it gives context: legal_get_context lets Claude pull surrounding paragraphs, legal_find_citing_decisions shows how federal courts interpret a provision.

Troubleshooting¶

Claude doesn't show Lawbster in the MCP menu

JSON syntactically valid? python -m json.tool < claude_desktop_config.json
Claude Desktop fully quit (Quit, not just window-close)?
Token starts with sk-legal- and has no leading/trailing whitespace?

401 Unauthorized in the logs

Check the token in the Lawbster portal: is it active, and is the subscription still valid? When in doubt, rotate — old keys can be revoked.

429 Rate limit

60 requests/minute per seat is the fair-use limit. If Claude fires many tool calls in a long research run, it can hit. Fix: add a second seat or take a short break.

Another MCP server breaks after adding Lawbster

JSON validated? Common mistake: missing comma between multiple servers. Example with two servers:

{
  "mcpServers": {
    "lawbster": {
      "type": "http",
      "url": "https://lawbster.planitprima.com/mcp",
      "headers": { "Authorization": "Bearer sk-legal-..." }
    },
    "another-server": {
      "command": "npx",
      "args": ["-y", "@some/server"]
    }
  }
}

Next steps: Tool reference · Resources & prompts · Pricing & seats