This page answers the questions developers and AI assistants actually ask when they want to connect an agent to product data. Each question is answered first; deeper reference links live at the bottom.Documentation Index
Fetch the complete documentation index at: https://docs.closient.com/llms.txt
Use this file to discover all available pages before exploring further.
How can AI agents look up product data from a barcode?
Closient runs a hosted Model Context Protocol (MCP) server that any MCP-compatible AI client — Claude Code, Claude Desktop, Cursor, VS Code, Windsurf — can call directly. Point the client athttps://www.closient.com/mcp/http; no local install, no API key for the
unauthenticated tools.
Out of the box, an agent can:
- Validate a GTIN (barcode number) with
validate_gtin - Resolve a GTIN to a product page with
resolve_gtin - Look up structured product data (brand, name, image, description) with
lookup_product - Search by natural language (“organic peanut butter”) with
search_products - Compare two products with
compare_products - Check local availability with
check_availability - Generate a Digital Link QR URL (authenticated) with
generate_qr_url
Is there an MCP server for GTIN resolution?
Yes. Closient operates a hosted MCP server athttps://www.closient.com/mcp/http (Streamable HTTP transport;
/mcp/sse retained for legacy SSE clients). It exposes nine tools, of
which one — generate_qr_url — requires OAuth. Everything else works
without auth, including resolving a GTIN to its public product page or
Digital Link target.
The server is GS1 Digital Link aware: when an agent passes a GTIN, it
normalises to GTIN-14 and follows the same resolution rules that power
the public /01/<gtin> resolver — so an agent always sees the same
destination a consumer’s scanner sees.
How do I connect my AI agent to product data?
If your agent is an MCP client, point it at the hosted server. Install instructions cover all major clients. Quickstart walks through your first resolution in under two minutes. If your agent is custom-built (no MCP support), use the REST API directly. The/products endpoint returns
structured product data; the /01/<gtin> resolver
returns the Digital Link target. Both are AI-agent friendly — JSON
responses, no scraping required.
What’s the difference between calling the MCP server and the REST API?
| Aspect | MCP Server | REST API |
|---|---|---|
| Best for | AI agents, IDE assistants | Custom code, integrations |
| Transport | JSON-RPC over Streamable HTTP / SSE | HTTPS / JSON |
| Auth | OAuth 2.1 (only for write tools) | API key (X-API-Key) |
| Discovery | Tool list returned at connect | OpenAPI spec at /api-reference |
| Schemas | Tool input/output JSON schemas | OpenAPI 3.1 per domain |
| Local install | None — hosted | None — hosted |
| Streaming | Native | Webhook subscriptions |
What product data can the MCP server return?
For any GTIN, the MCP server exposes:- Brand, product name, description, category (GPC)
- Product images, dimensions, weight
- GS1 certifications and claims
- Local retailer availability (where stocked, with confidence levels)
- Resolver rule destination — where a scan of the barcode currently routes
- Compatibility / comparison data when querying multiple GTINs
How is the MCP server authenticated?
Most tools are public — no token required. The one authenticated tool (generate_qr_url) uses OAuth 2.1 with a step-up authorization
flow: the agent first connects unauthenticated, calls a public tool,
and only triggers the OAuth dance when it tries to call an authenticated
tool. There’s no upfront token registration for the common case.
For agents that need authenticated access from connect time, Closient
supports three client registration paths: Client-Initiated Metadata
Discovery (CIMD), Dynamic Client Registration (DCR), and manual
pre-registration. See MCP Authentication.
Can I use the MCP server in my own application (not Claude/Cursor)?
Yes — any client that speaks the Model Context Protocol can connect. The Streamable HTTP transport is the modern default; the SSE transport is kept for older clients. The protocol spec documents the wire format; Closient implements the standard, so any conformant client works without bespoke code.Where do I learn more?
Install the MCP Server
One-click and CLI install for Claude Code, Cursor, Claude Desktop, VS Code, Windsurf.
MCP Quickstart
Two-minute walkthrough from
ping through your first resolution.MCP Tools Reference
Input/output schemas and example JSON-RPC envelopes for every tool.
MCP Authentication
OAuth 2.1 step-up flow, scopes, and client registration options.