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Syl Guardian

Official registry AI and agents

Causal guardrail: pass/caution/hold verdict on a causal claim before an agent acts.

Source code Website Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

Remote (streamable-http)
Claude Code 
claude mcp add --transport http syl-guardian 'https://guardian.sylai.io/mcp' --header 'X-API-Key: <Your Syl Guardian API key (get a trial key at https://sylai.io/guardian).>'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "syl-guardian": {
            "type": "http",
            "url": "https://guardian.sylai.io/mcp",
            "headers": {
                "X-API-Key": "<Your Syl Guardian API key (get a trial key at https://sylai.io/guardian).>"
            }
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. Syl Guardian MCP
  2. Connect
  3. Tool: guardian_review
  4. Support
  5. License

Syl Guardian MCP

Syl Guardian is a causal guardrail for AI agents. Before an agent acts on a claim like "ad spend drove new customers", Guardian checks it against your data and returns a pass, caution or hold verdict, with the naive correlation versus the confounder-adjusted causal effect, a confidence score and a plain-English recommendation.

All numbers are deterministic statistics. They are never generated by an LLM; only the interpretation prose may be AI-written.

This repository holds the public listing metadata and connection instructions for the hosted Guardian MCP server. Guardian itself is a hosted service.

Connect

Claude Code:

claude mcp add --transport http syl-guardian https://guardian.sylai.io/mcp \
  --header "X-API-Key: <your key>"

Claude Desktop (via mcp-remote):

{
  "mcpServers": {
    "syl-guardian": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://guardian.sylai.io/mcp",
               "--header", "X-API-Key:${SYL_API_KEY}"],
      "env": { "SYL_API_KEY": "<your key>" }
    }
  }
}

Then ask your agent: "Use guardian_review on this data: did ad_spend cause new_customers? Treat seasonality as a confounder."

Listing the tools does not require a key. A key is checked when guardian_review is called, and each review counts against your plan or trial quota.

Tool: guardian_review

Sanity-checks a causal claim before an agent acts on it.

ArgumentDescription
cause, effectRequired. Column names for the claim.
csv or dataDataset as CSV text or a list of row objects (exactly one).
known_confoundersOptional. Columns to adjust for; otherwise discovered automatically.
contextOptional business context, e.g. "Q3 promo evaluation".
units, stepDisplay-only unit hints; a treatment step to restate the effect in business terms.
time_col, adstock, seTime-series handling: row ordering, carryover effects, standard-error flavor.
test_designtrue or options. Also returns how long a spend-cut test needs to run.

The result includes a text summary (verdict, recommended action, effect versus correlation, interpretation) and the full structured response. Bad input, auth failures and quota errors come back as MCP tool errors with a descriptive message.

Support

Questions or issues: https://sylai.io or connor@sylai.io.

License

The files in this repository (metadata and documentation) are MIT licensed; see LICENSE. The Syl Guardian service is proprietary.

Frequently asked questions

What is Syl Guardian?

Causal guardrail: pass/caution/hold verdict on a causal claim before an agent acts.

How do I install Syl Guardian?

It runs as a remote server. In Claude Code: claude mcp add --transport http syl-guardian 'https://guardian.sylai.io/mcp' --header 'X-API-Key: <Your Syl Guardian API key (get a trial key at https://sylai.io/guardian).>'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does Syl Guardian need an API key?

Yes. It expects X-API-Key, which you set in its configuration.

Is Syl Guardian open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains Syl Guardian?

It is published by connor274. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.