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FabTally Guard

Official registry Security

Verify before you act: deps-check, x402-preflight, json-repair & url-read for agents.

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 fabtally-guard 'https://guard.fabtally.com/mcp'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "fabtally-guard": {
            "type": "http",
            "url": "https://guard.fabtally.com/mcp"
        }
    }
}

Documentation

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

FabTally Guard — MCP server

De-risk-a-dollar verification checks an AI agent runs before a costly action. Fronts the Guard HTTP API at **https://guard.fabtally.com**. Holds no private key.

Tools (all paid; a call with no payment returns the decoded x402 402 challenge)

ToolPriceWhat it does
deps_check$0.003Vet a package before installing — OSV.dev CVEs, typosquat similarity, deprecation/yank, SPDX license, age/download signals + a plain-English risk verdict. Args: ecosystem (npm\pypi\crates), name, version?.
x402_preflight$0.002Verify another x402 endpoint before paying it — valid x402 v2 402 challenge? price/asset/network/payTo consistent with its /.well-known/x402? TLS/reachability/openapi? + the parsed price. Args: url.
json_repair$0.002Coerce near-miss LLM JSON to a JSON-Schema-conformant object (fences/commas/quotes/keys/literals/brackets, then type-coerce, defaults, drop extras) — or precise per-field errors. Args: json (string), schema.
url_read$0.004Fetch a public url → clean Markdown + token estimate for RAG. Respects robots.txt, public pages only, nothing stored. Args: url.

Every tool also accepts an optional x_payment (base64 x402 payload) that is forwarded as the X-PAYMENT header to settle the call and return the real result. Humans can instead prepay by card and use an X-FabTally-Key credit key against the HTTP API.

Transports

  • stdio (portable): npx fabtally-guard-mcp (bin: fabtally-guard-mcp)
  • streamable-http (hosted): https://guard.fabtally.com/mcp

Config: FABTALLY_GUARD_BASE (default https://guard.fabtally.com).

Read-only, keyless, stateless, descriptive. Operated by Sunstone Soft (fabtally.com). Not a security guarantee.

Frequently asked questions

What is FabTally Guard?

Verify before you act: deps-check, x402-preflight, json-repair & url-read for agents.

How do I install FabTally Guard?

It runs as a remote server. In Claude Code: claude mcp add --transport http fabtally-guard 'https://guard.fabtally.com/mcp'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does FabTally Guard need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is FabTally Guard open source?

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

Who maintains FabTally Guard?

It is published by zvmzaretsky. 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.