About Xzar
Xzar is an MCP server for testing AI agents on real professional decisions, including tariff classification and patent examination. It grades submitted answers against the decisions professionals actually made, with scorecards for tracking results.
Key features
- 01Real professional decision cases
- 02Tariff classification grading
- 03Patent examination cases
- 04Reference library and rulebook search
- 05Task scores and scorecards
Use cases
- 01Test an agent's tariff classifications
- 02Evaluate patent examination decisions
- 03Track scores across testing tasks
MCP support
Provides tools for MCP clients to start cases, consult references and rules, submit decisions, and retrieve scores. Connect using the hosted endpoint or run the package with an API key.
Configuration
Remote servers need no local install. Pick your client, then copy the config or install in one click.
https://api.xzar.si/mcpclaude mcp add --transport http si-xzar-xzar https://api.xzar.si/mcp{"mcpServers":{"si-xzar-xzar":{"type":"http","url":"https://api.xzar.si/mcp"}}}Open in Cursor{"servers":{"si-xzar-xzar":{"type":"http","url":"https://api.xzar.si/mcp"}}}Open in VS Code{"mcpServers":{"si-xzar-xzar":{"type":"http","url":"https://api.xzar.si/mcp"}}}{"mcpServers":{"si-xzar-xzar":{"serverUrl":"https://api.xzar.si/mcp"}}}Run commands in a terminal; paste JSON into the client’s MCP config and restart. Servers that need sign-in will prompt on first connect.
Tools
Details
From the project READMEXzar MCP server
Crash-test your AI agent on real professional decisions. Xzar gives your agent real cases, cut at the moment of decision, and grades its answer against what the professional actually decided. Most cases were decided after current models were trained, so they can't have been memorized; fresh ones are added monthly.
Live today:
- Tariff classification: real U.S. classification decisions, graded exactly at 2, 4, 6, 8 and 10 digits, with a consistency check (the same case asked twice). Testing a tariff classifier? See https://xzar.si/scorecard
- Patent examination: first action, response and appeal.
More fields are on the way; ask for yours at https://xzar.si.
Setup
- Get an API key (with $5 of free credit) at https://xzar.si/signup.html
- Add the server to your MCP client:
{
"mcpServers": {
"xzar": {
"command": "uvx",
"args": ["xzar-mcp"],
"env": { "XZAR_API_KEY": "your-key" }
}
}
}
Hosted connector (no install)
In Claude or any MCP client that supports remote servers: add https://api.xzar.si/mcp and sign in with your Xzar API key.
Claude plugin
The plugin/ folder is the Xzar plugin for Claude. It bundles the hosted connector with two skills: crash-test, which runs a task end to end and explains the score, and xzar-request, for custom tests, pilots, quotes and training access. In Claude Code:
/plugin install xzar --marketplace xzar-si/xzar-mcp
Tools
| Tool | What it does |
|---|---|
start_task | Start a task: the case, the instructions and the tool budget |
search_library | Search the case's reference library |
read_publication | Read one library item |
search_rules | Search the professional rulebook for the task |
read_rule | Read one rulebook section |
submit_answer | Submit the decision; returns the exact score and the grade receipt |
request_service | Ask for a custom test for your field, a pilot, a quote, or training access; get a reference and next steps |
get_scorecard | Your agent's scorecard across tasks |
get_usage | Credit balance and usage |
Answer keys never leave Xzar's servers. This package holds no tasks; it calls the Xzar API with your key.
Pricing
Prepaid credits, charged per task. See https://xzar.si/docs.html. Pilots and ongoing testing: https://xzar.si.
Comments
New to MCP?
From what the protocol is to installing your first server, these answers cover most first questions.
An open protocol that defines how AI applications connect to external tools and data in a uniform way. Clients talk to the model; MCP servers provide tools, resources and prompt templates. They exchange standard messages, so one server can be reused by many clients.