Ground Truth

Live fact-checking tools for AI agents.

Ground Truth gives AI agents read-only verification tools for live public data: free endpoint reachability checks, free security-header inspection, pricing-page scans, pricing-page comparisons, evidence-backed claim checks, package-market sizing, compliance scans, named package comparisons, and multi-step hypothesis tests.

You can use Ground Truth three ways:

• Free endpoint and security-header checks for lightweight verification
• Agentic pay-per-use with x402-compatible clients or an xpay proxy
• A team subscription with X-API-Key billing and predictable monthly usage

Live: https://ground-truth-mcp.anishdasmail.workers.dev

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Try This First

These two tools work without signup or an API key:

• check_endpoint: verify that a public URL or API endpoint responds.
• inspect_security_headers: inspect HSTS, CSP, frame protections, and related browser-facing security headers.

Example prompts:

• "Use Ground Truth to check whether https://api.github.com responds."
• "Use Ground Truth to inspect security headers for https://example.com."
• "Before recommending this API, use Ground Truth to verify the endpoint is reachable."

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What Ground Truth Verifies

Ground Truth helps agents check facts before they answer, recommend, or act.

Verification	What it checks	Example
Pricing claims	Pulls live pricing from product pages	"Does Stripe have a free tier?"
Pricing comparisons	Compares multiple pricing pages side by side	"Which vendor shows a free trial right now?"
Compliance posture	Scans trust pages for enterprise signals	"Does this vendor mention SOC 2, GDPR, and SCIM?"
Security posture	Inspects browser-facing security headers	"Does this app expose HSTS and CSP?"
Competitor existence	Checks whether real alternatives show up in npm or PyPI	"Are there edge-first Prisma alternatives?"
API endpoints	Confirms a URL exists and responds	"Does this endpoint return 200?"

All results come from live data and are cached for 5 minutes for faster repeat checks.

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Complementary MCP Servers

Ground Truth is strongest when paired with a broader discovery or browser tool:

• Tavily MCP Server for real-time web search and content discovery before you run a claim or pricing check.
• Firecrawl MCP Server for deeper crawling and JS-heavy page extraction when raw HTML heuristics are not enough.
• mcp-server-browserbase for interactive browser verification on pages that need clicks, auth, or client-side rendering.

These are complementary to Ground Truth rather than substitutes: they help you find or render the page, while Ground Truth helps you verify the resulting claim.

If you are filling in Glama related servers for this project, start with these three:

• Tavily MCP Server
• Firecrawl MCP Server
• mcp-server-browserbase

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Why AI Agents Need Verification

Training data goes stale. Docs change. Pricing changes. Competitors appear. Endpoints break. Policies move.

Ground Truth gives agents a way to check before they commit:

• Before quoting a price, pull the live pricing page
• Before comparing vendors, scan their live pricing pages side by side
• Before repeating a compliance claim, scan the live trust page
• Before asserting a security baseline, inspect the response headers
• Before saying a competitor does not exist, search the live registry
• Before recommending an API, confirm the endpoint responds
• Before calling one package more popular, compare real package metadata
• Before repeating a policy, verify the language on the current public page

The result is simple: agents that are less confident for the wrong reasons and more reliable when it matters.

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Example Workflows

Verify a pricing claim

"Notion costs $8 per user per month for teams."

Use check_pricing on the live pricing page before repeating the number.

Check whether a competitor exists

"There is no good edge ORM alternative to Prisma."

Use estimate_market to search npm for edge orm and see what already exists.

Compare vendor pricing pages

"Vendor A is cheaper than Vendor B."

Use compare_pricing_pages to compare live pricing pages before repeating the claim.

Scan a trust page

"This vendor supports SOC 2, GDPR, and SCIM."

Use assess_compliance_posture before treating that as current fact.

Inspect browser-facing security headers

"This app has a strong public security baseline."

Use inspect_security_headers before making the claim.

Validate an API endpoint

"Use the OpenAI /v1/models endpoint to list available models."

Use check_endpoint before recommending it in docs, code, or support replies.

Compare package popularity

"Vue has overtaken React."

Use compare_competitors to compare live package metadata instead of guessing.

Test a market assumption

"There are fewer than 50 MCP tools on npm."

Use test_hypothesis with a count-based check and return the actual result.

Confirm whether a support policy applies

"AWS Business support includes 24/7 phone support."

Use verify_claim against the current AWS support page before treating that as fact.

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Access Modes

Free

Free tier includes limited monthly endpoint and security-header checks.

• check_endpoint
• inspect_security_headers
• 100 requests per calendar month
• Tracked by Cloudflare client IP in production, or X-Anonymous-Client-Id for local/dev testing
• No signup or API key required

Agentic pay-per-use

Paid tools also support agentic pay-per-use.

• Use an x402-compatible MCP client, or put an xpay MCP proxy in front of this server
• Tool pricing starts at $0.01 per call and varies by tool
• Best for autonomous agents or variable workloads
• Includes estimate_market, check_pricing, compare_pricing_pages, compare_competitors, verify_claim, assess_compliance_posture, and test_hypothesis

Team

Team subscription uses API-key billing with predictable monthly usage.

• Requires X-API-Key with active billing
• Default quota of 5,000 requests per calendar month
• Monthly usage tracked per API key and tool
• Includes all paid verification tools

View pricing

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API Examples

Direct API with curl

Direct HTTP calls to /mcp are session-based. Initialize once, keep the returned mcp-session-id, then call tools with that header.

The examples below use the team plan with X-API-Key. For agentic pay-per-use, use an x402-capable MCP client or put an xpay proxy in front of this server.

SESSION_ID="$(curl -i -s -X POST https://ground-truth-mcp.anishdasmail.workers.dev/mcp \
  -H "Accept: application/json, text/event-stream" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "initialize",
    "params": {
      "protocolVersion": "2025-03-26",
      "capabilities": {},
      "clientInfo": {
        "name": "ground-truth-example",
        "version": "1.0.0"
      }
    },
    "id": 0
  }' | tr -d '\r' | awk '/^mcp-session-id:/ {print $2}')"

curl -X POST https://ground-truth-mcp.anishdasmail.workers.dev/mcp \
  -H "Accept: application/json, text/event-stream" \
  -H "Content-Type: application/json" \
  -H "Mcp-Session-Id: $SESSION_ID" \
  -H "X-API-Key: $GROUND_TRUTH_API_KEY" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "check_pricing",
      "arguments": {
        "url": "https://stripe.com/pricing"
      }
    },
    "id": 1
  }'

JavaScript fetch

const initResponse = await fetch("https://ground-truth-mcp.anishdasmail.workers.dev/mcp", {
  method: "POST",
  headers: {
    "Accept": "application/json, text/event-stream",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    jsonrpc: "2.0",
    method: "initialize",
    params: {
      protocolVersion: "2025-03-26",
      capabilities: {},
      clientInfo: {
        name: "ground-truth-example",
        version: "1.0.0",
      },
    },
    id: 0,
  }),
});

const sessionId = initResponse.headers.get("mcp-session-id");

if (!sessionId) {
  throw new Error("Missing mcp-session-id from initialize response");
}

const response = await fetch("https://ground-truth-mcp.anishdasmail.workers.dev/mcp", {
  method: "POST",
  headers: {
    "Accept": "application/json, text/event-stream",
    "Content-Type": "application/json",
    "Mcp-Session-Id": sessionId,
    "X-API-Key": process.env.GROUND_TRUTH_API_KEY,
  },
  body: JSON.stringify({
    jsonrpc: "2.0",
    method: "tools/call",
    params: {
      name: "compare_competitors",
      arguments: {
        packages: ["react", "vue"],
        registry: "npm",
      },
    },
    id: 1,
  }),
});

const result = await response.json();
console.log(result);

Free endpoint check

curl -X POST https://ground-truth-mcp.anishdasmail.workers.dev/mcp \
  -H "Accept: application/json, text/event-stream" \
  -H "Content-Type: application/json" \
  -H "Mcp-Session-Id: $SESSION_ID" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "check_endpoint",
      "arguments": {
        "url": "https://api.github.com"
      }
    },
    "id": 1
  }'

Lightweight request checks for free access, team-plan billing, invalid keys, inactive billing, quota enforcement, and active paid access live in test-usage-enforcement.sh.

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MCP Setup

If you use Claude Desktop, Cursor, or another MCP client, Ground Truth can plug in as a verification tool for your agent.

MCP stands for Model Context Protocol. It is the standard that lets AI apps call external tools.

If you want agentic pay-per-use without changing your app code, register this MCP URL with xpay and share the resulting proxy URL instead.

Claude Desktop

Add this to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "ground-truth": {
      "url": "https://ground-truth-mcp.anishdasmail.workers.dev/mcp",
      "headers": {
        "X-API-Key": "gt_live_your_key_here"
      }
    }
  }
}

Cursor

Add this to .cursor/mcp.json in your project or ~/.cursor/mcp.json globally:

{
  "mcpServers": {
    "ground-truth": {
      "url": "https://ground-truth-mcp.anishdasmail.workers.dev/mcp",
      "headers": {
        "X-API-Key": "gt_live_your_key_here"
      }
    }
  }
}

Claude Code skill

If you want the same workflow without running a server, see claude-skill/.

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Use Cases

Support

• Verify a pricing claim before sending it to a customer
• Check whether a support policy applies before escalating
• Confirm an API endpoint exists before recommending it in a reply
• Inspect public security headers before repeating a security claim

Product

• Test whether a market assumption is true before writing a spec
• Check whether a competitor exists before framing a roadmap
• Compare package popularity before making a platform choice
• Compare pricing pages before telling a team one vendor is cheaper

Compliance

• Scan trust pages for SOC 2, GDPR, HIPAA, DPA, SSO, and SCIM signals
• Verify pricing or packaging claims before repeating them internally
• Check that a public terms or policy URL is reachable and current

Security & vendor diligence

• Compare competitor pricing across live pages
• Inspect browser-facing security headers before recommending or approving a vendor
• Validate positioning claims with structured checks

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Tool Reference

Tool	Tier	What it does
check_endpoint	Free	Checks whether a URL or API endpoint exists and responds
estimate_market	Paid	Counts packages in npm or PyPI for a search term
check_pricing	Paid	Extracts prices, plans, and free-tier signals from a page
inspect_security_headers	Free	Checks common browser-facing security headers on a public URL
compare_pricing_pages	Paid	Compares multiple live pricing pages side by side
compare_competitors	Paid	Compares packages side by side with live metadata
verify_claim	Paid	Checks whether live sources support or contradict a claim
assess_compliance_posture	Paid	Scans a trust page for compliance and enterprise-security signals
test_hypothesis	Paid	Runs pass/fail tests against a live-data assumption

Full reference: API_USAGE.md

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Architecture

Ground Truth keeps the current Cloudflare Workers architecture:

• Runtime: Cloudflare Workers
• Storage: Durable Objects with SQLite for cache and usage logs
• API keys: Cloudflare KV
• Billing: Stripe team subscriptions plus x402-compatible pay-per-use
• Protocol: MCP
• Language: TypeScript

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Distribution

Ground Truth is set up for multiple discovery and monetization paths:

• Official MCP Registry publishing through server.json for ecosystem-wide discovery.
• Smithery URL publishing. This server exposes Streamable HTTP at /mcp and a static server card at /.well-known/mcp/server-card.json for metadata fallback.
• xpay MCP monetization. You can register the live /mcp URL with xpay to get a managed pay-per-tool proxy without changing the server code.
• MCP Market directory listing for additional discovery.
• Apify is optional if you want a separate marketplace-native Actor version later; the current project stays optimized for remote MCP delivery rather than an Actor-first runtime.

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Development

cd ground-truth-mcp
npm install
npx wrangler dev

Deployment notes live in SETUP.md.

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GitHub Releases

Stable GitHub releases are created automatically when you push a version tag that matches v*.

git tag v0.4.0
git push origin v0.4.0

That tag triggers .github/workflows/release.yml, which typechecks the project and publishes a GitHub release from the tag. This is the repo-side piece Glama uses to detect stable releases during maintenance scans.

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Glama Release

Glama releases are Docker-based, not GitHub releases. This repo includes a Dockerfile that starts the Worker locally through Wrangler on port 3000.

docker build -t ground-truth-mcp .
docker run --rm -p 3000:3000 ground-truth-mcp

For the Glama flow:

1. Claim the server in Glama.
2. Open the Dockerfile admin page, use this repository Dockerfile, and run the deploy test.
3. After the deploy test succeeds, click Make Release, choose a version, and publish.
4. If the score page still shows No LICENSE, trigger a re-scan in the Glama admin interface after GitHub has recognized the root LICENSE file.
5. If the score page still shows No related servers, use Add related servers in the claimed Glama UI and add Tavily MCP Server, Firecrawl MCP Server, and mcp-server-browserbase. That checklist item is managed on Glama's side rather than in glama.json.

If Glama generates an mcp-proxy-based build spec instead of using the repository Dockerfile, point the command at npm run start:glama:stdio. That bridge exposes the existing remote Ground Truth MCP endpoint over stdio so mcp-proxy can host it.

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Documentation

• API_USAGE.md for API calls and tool arguments
• SETUP.md for deployment and billing setup
• claude-skill/ for the zero-deployment Claude Code version

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Support

• Email: anishdasmail@gmail.com
• Website: https://ground-truth-mcp.anishdasmail.workers.dev/

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License

MIT — see LICENSE

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Made by Anish Das

Last updated: April 29, 2026