BestPrice

BestPrice MCP

The official Model Context Protocol server for BestPrice.gr, Greece's price-comparison service. It gives AI assistants read-only access to shopping decisions, live product search, offer comparison, and price history. No account or API key is needed.

Start shopping

• Open BestPrice in ChatGPT and add the published plugin.
• Connect BestPrice to Claude using the prefilled connector form.
• See the shopping guide for examples and other assistants.

For developer integrations, the public endpoint is:

https://mcp.bestprice.gr/mcp

• Transport: Streamable HTTP over HTTPS; anonymous shopping, optional OAuth for Events
• Official Registry ID: gr.bestprice/mcp
• Server version: 1.8.4
• Public guide: https://www.bestprice.gr/mcp
• Support: https://www.bestprice.gr/contact

This repository holds everything that lives outside the hosted service: the install manifests for each AI client, a local stdio bridge for hosts that cannot speak HTTP, and the browser-native WebMCP layer. The server itself is not in this repository.

The current release matrix records the live gateway, UI, OAuth/Events, plugin review and separate ACP qualification.

Tools

Tool	What it does	Key arguments
get_shopping_decision	Runs the BestPrice Shopping Brain: an evidence-backed recommendation, need-based comparison, or read-only basket plan with reasons, tradeoffs, and unknowns.	message (the need in Greek or English, including any budget), optional postal_code (required for a completed basket plan), optional evidence_detail (summary, the default: only the evidence the answer cites; full: every claim and source)
search_products	Finds canonical products in the catalog. Returns product IDs and the catalog minimum price before shipping.	query (2–200 characters: a name, model, category, or a bare GTIN/EAN barcode), optional price_min, price_max, required_features, sort (relevance, price_asc, price_desc), limit (1–8)
compare_offers	Compares current merchant offers for one exact product, separating item price, shipping, and delivered total.	product_id from a previous result, optional postal_code (a Greek postcode, 10000–85999, for delivered totals), objective, in_stock_only, minimum_merchant_rating, limit (1–10)
get_price_history	Summarises how a product's price moved over time, against its 180-day median.	product_id, optional period_days (30, 90 or 180)

All four tools are read-only. They never place orders, create alerts, or read account data. Results link to a BestPrice product page, never directly to a merchant. Unknown shipping is reported as unknown, not as free. Search covers safe physical products; digital goods, services, and age-restricted categories are excluded.

Protocol details

Measured against the live endpoint on 24 September 2026.

• Versions. initialize negotiates 2025-11-25, 2025-06-18, 2025-03-26, 2024-11-05 and 2024-10-07; a client that asks for any other version is answered with 2025-11-25. The 2026-07-28 per-request revision is also served: send the MCP-Protocol-Version, Mcp-Method (and, for tools/call, Mcp-Name) headers, and put io.modelcontextprotocol/protocolVersion and io.modelcontextprotocol/clientCapabilities in every request's _meta. A request that names the revision without that envelope is refused with -32602.
• Stateless. No MCP-Session-Id is issued and none is required; DELETE answers 405. A GET with Accept: text/event-stream opens a keep-alive stream, but the server never sends requests or notifications on it, so a client loses nothing by not opening it.
• Capabilities. tools and resources are available to compatible clients. The resource surface contains the optional MCP Apps UI at ui://bestprice/shopping-results-v1.html, the server card at mcp://server-card.json, and the canonical skill://bestprice-shopping/SKILL.md. On MCP 2026-07-28 the server also declares the final io.modelcontextprotocol/skills extension: skills/list and skills/get return the one BestPrice Shopping Skill with its SHA-256 digest and byte size, and resources/read returns the exact markdown bytes. Older clients simply see the Skill as an ordinary resource. There are no prompts, completions or logging; those methods answer -32601.
• Responses. A client that accepts both application/json and text/event-stream gets a one-event SSE response. Accept: application/json, */* or no Accept header gets a single JSON body. Every tool returns structuredContent that validates against its outputSchema, plus the same result as text for clients that do not pass structured content to the model.
• Errors. An unknown tool is a JSON-RPC error (-32602). Invalid arguments and service failures such as an unknown product are tool results with isError: true, so the model can read and correct them.
• Limits. JSON request bodies up to 256 KiB (413 above that), a 12-second request deadline, and per-client rate limits answered with HTTP 429, JSON-RPC error -32029 and a Retry-After header. JSON-RPC batch arrays are refused with 400.
• Browsers. Desktop, CLI and server-side clients send no Origin header and are not affected. A browser page may call the endpoint from an allowlisted AI-host origin, from bestprice.gr, or from localhost (so MCP Inspector works in direct mode); any other origin gets 403.
• Authentication. The four shopping tools work without an account. Optional account linking is scoped to events:subscribe; protected-resource metadata is available at /.well-known/oauth-protected-resource and /mcp/oauth-protected-resource. Events remains disabled during end-to-end qualification.

Developer quick start

Every client below connects to the same endpoint. Detailed, provider-specific instructions including OpenAI, Grok, GitHub Copilot, and Microsoft Copilot Studio are in docs/provider-setup.md.

Claude

Connect BestPrice to Claude opens the custom-connector flow with the endpoint prefilled. For Claude Code:

claude mcp add --transport http bestprice-shopping https://mcp.bestprice.gr/mcp

The bundled .mcp.json is the equivalent project-scoped configuration.

Cursor

Add BestPrice to Cursor shows the decoded configuration before adding it. The .cursor-plugin/ directory holds the marketplace plugin and an agent skill.

VS Code

Add BestPrice to VS Code

Gemini CLI and Qwen Code

gemini extensions install https://github.com/TheBestCo/bestprice-mcp
qwen extensions install https://github.com/TheBestCo/bestprice-mcp --consent

Both extensions restrict the imported tools to the four listed above.

Codex, Claude plugins, and Agent Skill hosts

The root plugin.json, mcp.json, and skills/bestprice-shopping/SKILL.md form a portable Agent Plugins package: the MCP supplies live shopping data and the Skill teaches the host when and how to route unbranded Greek shopping intent. Agent-compatible hosts that discover repository-local skills under .agents/skills/ get the same canonical workflow at .agents/skills/bestprice-shopping/SKILL.md. .codex-plugin/ remains the Codex compatibility manifest. .claude-plugin/plugin.json plus the same root Skill and .mcp.json also make this repository a Claude plugin package.

Self-hosted plugin marketplaces

The same repository can be added directly as a plugin marketplace, with no copied tool or Skill logic:

copilot plugin marketplace add TheBestCo/bestprice-mcp
copilot plugin install bestprice-shopping@bestprice

claude plugin marketplace add TheBestCo/bestprice-mcp
claude plugin install bestprice-shopping@bestprice

Copilot reads .github/plugin/marketplace.json and, under Agent Plugins 1.0, loads the canonical root plugin.json, mcp.json, and skills/bestprice-shopping/SKILL.md. Claude reads .claude-plugin/marketplace.json and uses .claude-plugin/plugin.json, .mcp.json, and the same root Skill.

Gemini API, DeepSeek, Z.ai

Runnable examples live in examples/: the Gemini Interactions API and Genkit, a DeepSeek Harness plugin entry, and a Z.ai GLM call. Each needs the provider's own API key. BestPrice needs none.

Any other MCP client

Add a Streamable HTTP server at https://mcp.bestprice.gr/mcp. If the host only supports stdio servers, use the bridge in this repository:

git clone https://github.com/TheBestCo/bestprice-mcp.git && cd bestprice-mcp
npm ci
node stdio.mjs

The bridge forwards everything to the public endpoint and accepts two environment variables: BESTPRICE_MCP_URL (default: the public endpoint) and BESTPRICE_MCP_TIMEOUT_MS (default: 60000). A Dockerfile builds the same bridge for Glama and similar hosts.

A safe first conversation

1. Ask for a decision: Θέλω κινητό έως 500 ευρώ με NFC και 5G υποχρεωτικά. (I want a phone up to 500 euros, NFC and 5G required.)
2. Or search: Find Sony WH-1000XM5 under 300 euros.
3. Pass a returned product_id to compare_offers with postal code 10558.
4. Pass the same product_id to get_price_history for 180 days.

Queries work in Greek or English. Result summaries, catalog data and merchant names come back in Greek.

Search	Compare offers	Price history

Browser-native WebMCP

BestPrice pages register 22 contextual WebMCP tools (contract 2.8) in compatible browsers — each one reads or acts, never both — covering search with structured results (narrowed by price, stock, deals and order) and opening the results page a search returned in the tab, the shopper's shopping list and comparisons (read everywhere, added to and removed from on a product page), a price-drop alert dialog, the visible products and loading more, filters and sorting, opening any product by id (read before the tab moves), product facts, offers, specifications and price history (with its chart), one visible-offer action, and the BestPrice Shopping Brain — on every public page, articles and stores included — while leaving the merchant choice to the shopper. Every tool publishes an input and an output schema. The contracts, fail-closed runtime, deterministic evaluator, and the 47-case natural-language dataset are in webmcp/.

Discovery

• Official MCP Registry
• Open agent discovery: ard.json, ai-catalog.json, server card, and the provider-neutral BestPrice Shopping skill. The ARD examples are deliberately unbranded shopper intents so discovery can match “what should I buy?”, delivered-price, and price-timing requests before a user knows BestPrice.
• webmcp.json describes the contextual browser tools exposed by BestPrice pages.
• The repository is listed in the Gemini CLI extension gallery as bestprice-shopping (Google crawls tagged public extension repositories), while GitHub Agent Finder can ingest the public MCP catalog and ARD resources.
• Copy-ready, CI-pinned external catalog contributions live under distribution/: a GitHub Agent Finder Skill entry and a Docker MCP Registry remote-server entry. Those catalogs require review in their own repositories; the checked-in files are submission payloads, not claims that the external listings are already live.
• Community indexes: Glama, WebMCP Registry, webmcp.com, cursor.directory

Development

npm ci
npm run check   # Biome lint and format
npm test        # node --test: bridge, WebMCP, manifests, dataset

Tests need no network: the bridge is exercised against an in-process fake remote. Node 20 or newer is required; .nvmrc pins 22.

Versioning

Two versions appear in this repository on purpose:

• Package version in package.json and every plugin or extension manifest. It changes when this repository's manifests, bridge, or WebMCP layer change, and is tagged vX.Y.Z.
• Server version in server.json and the line near the top of this README. It is the version the hosted service reports and is published to the official MCP Registry.

CHANGELOG.md tracks the package version.

Timestamped hosted-service checks are recorded separately. The 7 September Shopping Brain v12 verification includes its exact gateway revision, sanitized canary results, and scope limits.

Security

Report vulnerabilities privately as described in SECURITY.md.

Contributing

See CONTRIBUTING.md. Issues and pull requests are welcome.

License

Apache License 2.0. Copyright The Best Company S.A. See LICENSE.

Privacy: https://www.bestprice.gr/policies/privacy · Terms: https://www.bestprice.gr/policies/terms