Vaquill MCP Server

US legal research MCP for Claude, Cursor, VS Code, and Windsurf. USC + CFR + 50-state law + US case law.

The Vaquill MCP server gives any Model Context Protocol client - Claude.ai, Claude Desktop, Claude Code, Cursor, VS Code, Windsurf - direct access to the Vaquill legal research API. It covers US federal and 50-state law (USC, CFR, state legislation, and US case law). Source: github.com/Vaquill-AI/vaquill-mcp.

GitHub

Source code and issues

PyPI

uvx vaquill-mcp

Hosted endpoint

https://mcp.vaquill.ai

Quickstart

The fastest path is the hosted remote MCP on Claude.ai web - no install, no local Python, no config files.

Install Vaquill MCP in Claude Code with one paste. Replaces a manual config edit.

CopiedCopy prompt

1. Get an API key

   Generate a vq_key_... token from your dashboard settings. See Authentication.

2. Open Claude.ai Settings > Integrations

   Click Add a connector and pick Custom MCP server.

3. Paste the URL

   Use either the path-token form:

   https://mcp.vaquill.ai/s/vq_key_your_key_here
   

   Or, if your client supports auth headers, use the bearer-token form:

   URL:   https://mcp.vaquill.ai/s/_
   Token: vq_key_your_key_here
   
4. Ask a legal question

   Try: “What does 17 CFR 240.10b-5 say about insider trading?” - Claude will call ask_legal_question and return a grounded answer with citations.

Remote MCP connectors are available on Claude Pro, Max, Team, and Enterprise plans.

Client setup

Pick your client below. All configs accept the same set of environment variables - see Environment variables.

Claude Desktop

// ~/Library/Application Support/Claude/claude_desktop_config.json  (macOS)
// %APPDATA%\Claude\claude_desktop_config.json                       (Windows)
{
  "mcpServers": {
    "vaquill": {
      "command": "uvx",
      "args": ["vaquill-mcp"],
      "env": {
        "VAQUILL_API_KEY": "vq_key_your_key_here"
      }
    }
  }
}

The uvx runner requires Python 3.10+ and uv on PATH. uvx vaquill-mcp downloads and executes the package in an isolated env on first run; subsequent runs are instant.

Tools

The server exposes 15 tools across four categories. Credit costs match the pricing schedule and can be checked live with get_pricing.

General

Tool	Description	Credits
ask_legal_question	AI-powered legal Q&A across USC + CFR + 50-state law + US case law. Standard (fast) or deep (multi-hop) modes.	5 - 20
get_pricing	Get current API credit pricing. No auth required.	Free

US law (USC + CFR)

Tool	Description	Credits
search_us_statutes	Semantic search across the United States Code (USC) and Code of Federal Regulations (CFR). Filter by corpusType and titleNumber.	2
get_us_statute_section	Metadata for a specific USC / CFR section by act_id - citation, title hierarchy, links.	1
get_us_statute_section_text	Full HTML and plain text of a USC or CFR section.	3

Case law

Tool	Description	Credits
search_legal_cases	Boolean keyword search across the case-law corpus. AND / OR / NOT operators, court / year filters.	1 - 3
quick_search	Compact top 3 - 5 case results with essentials only.	1
resolve_citation	Resolve a citation to a canonical case record.	1
search_cases_by_citation	Search cases by citation text or case name with filters.	1
lookup_case	Full case details with citation treatment stats (followed, overruled, distinguished).	1
get_citation_network	Traverse the citation graph: 1 - 3 hops, inbound / outbound / both.	2

Acts and legislation

Tool	Description	Credits
search_legislation	Semantic search across acts, regulations, and state legislation. Filter by category, state, department, year.	1
list_legislation	Browse acts to discover act_id values. Filter by category, state, department, status.	1
get_act_text	URLs for full text, PDF, and HTML versions of an act.	1
get_amendments	Complete amendment history for an act (substitutions, insertions, omissions).	1

Authentication

The Vaquill MCP server authenticates with your Vaquill API key. Three options, in priority order:

1. Bearer header (remote): Authorization: Bearer vq_key_...
2. Path token (remote): https://mcp.vaquill.ai/s/vq_key_... - convenient when your client cannot send custom headers.
3. Environment variable (local): VAQUILL_API_KEY=vq_key_... for uvx / stdio launches.

Keys are scoped per workspace and revocable from the dashboard. For the full auth model, request signing, and rotation policy, see Authentication.

Treat the path-token URL as a secret - anyone with the URL can spend credits from your account. Prefer the bearer-token form whenever the client supports it.

Self-hosting

The MCP server is a thin wrapper around the public Vaquill API, so most users will not need to self-host. Run from source when you want to pin a version, add custom telemetry, or modify tool descriptions.

git clone https://github.com/Vaquill-AI/vaquill-mcp.git
cd vaquill-mcp
uv sync --all-extras

# Run locally over stdio
VAQUILL_API_KEY=vq_key_... uv run vaquill-mcp

# Inspect tools interactively
uv run fastmcp dev src/vaquill_mcp/server.py

The package fetches the OpenAPI spec from https://api.vaquill.ai at startup and auto-generates MCP tools with FastMCP. New API endpoints appear as tools automatically without a package upgrade.

Environment variables

Variable	Required	Default	Description
VAQUILL_API_KEY	Yes	-	Your API key (vq_key_...) from vaquill.ai/settings
VAQUILL_BASE_URL	No	https://api.vaquill.ai	API base URL. Override for staging or self-hosted API instances.
VAQUILL_TIMEOUT	No	120	Per-request timeout in seconds. Increase for deep-mode ask_legal_question calls.

Usage examples

Type these directly to Claude, Cursor, or any connected assistant.

US law

“What does 17 CFR 240.10b-5 say about insider trading?”

“Find USC sections on equal protection under the Fourteenth Amendment.”

“Summarize FRCP Rule 12(b)(6) and recent SDNY case law applying it.” (uses deep mode)

“What are the federal penalties for wire fraud under 18 USC 1343?”

“Pull the full text of 26 USC 501(c)(3).”

Ready-to-run research prompt

Brief a case with treatment stats. Paste into any Vaquill-connected assistant. Replace the citation.

CopiedCopy prompt

Pricing

API calls consume credits at $0.01 USD per credit. The get_pricing tool returns the live schedule and is free to call. Per-tool costs are listed in the Tools tables above.

Related

MCP overview

All Vaquill MCP servers at a glance

Integrations

Chatbots, widgets, browser extensions, and automation

Authentication

API key setup and rotation

Credits and pricing

How metering works

Ask a legal question (API)

The underlying REST endpoint