Ground Truth MCP Server

Ground Truth

Verification layer for AI agents.

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

Free tier includes limited monthly endpoint checks. Pro unlocks claim verification, market checks, competitor comparisons, and higher usage limits.

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

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What Ground Truth Verifies

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

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 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.

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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Free vs Pro

Free

Free tier includes limited monthly endpoint checks.

• Only check_endpoint
• 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

Pro

Pro unlocks claim verification, market checks, competitor comparisons, and higher usage limits.

• 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 check_pricing, verify_claim, estimate_market, compare_competitors, and test_hypothesis

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.

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, blocked Pro calls, invalid keys, inactive billing, quota enforcement, and active Pro 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.

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

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

Legal

• Confirm whether a support policy applies on a live public page
• Verify pricing or packaging claims before repeating them internally
• Check that a public terms or policy URL is reachable and current

Market research

• Compare competitor pricing across live pages
• Count category competitors before entering a space
• Validate positioning claims with structured checks

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Tool Reference

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 Checkout and subscriptions
• Protocol: MCP
• Language: TypeScript

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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 v0.3.1
git push origin v0.3.1

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
• Issues: https://github.com/anish632/ground-truth-mcp/issues

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License

MIT — see LICENSE

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Made by Anish Das

Last updated: April 29, 2026