Yampi MCP

An MCP server that lets you talk to your Yampi store from Claude — look up orders, create products, adjust stock, build coupons and offers.

Every merchant hosts their own copy on Cloudflare. This is not a service: nobody holds your credentials but you. Unofficial, and not affiliated with Yampi.

How it works

A Yampi credential belongs to the user, not the store: if you run four stores under one login, all four show up. You connect once and pick the store on each command.

Setup

You need a Cloudflare account (the free plan is enough) and Node installed.

git clone https://github.com/Eduardo-Orsi/yampi-mcp && cd yampi-mcp
npm install
cp wrangler.example.jsonc wrangler.jsonc
npx wrangler kv namespace create OAUTH_KV   # paste the returned id into wrangler.jsonc
npx wrangler deploy

In your Claude client (claude.ai, Desktop or Code), add a custom connector pointing at https://yampi-mcp.<your-subdomain>.workers.dev/mcp.

On connect, a screen asks for your User-Token and User-Secret-Key. You'll find them in the Yampi dashboard under Perfil › Credenciais de API (Profile › API Credentials). That's it — there's no password to create.

Using it

Once connected, it's plain conversation:

"How many paid orders did store X get between June 1st and 15th?" "Create a product called Black T-Shirt, brand Acme, SKU TS-BLACK-M, R$ 79.90, 20 in stock." "SKU TS-BLACK-M is priced wrong — change it to R$ 89.90 and drop stock to 5." "Which carts were abandoned this week and what do they add up to?" "Create a 15% coupon valid through month end, R$ 100 minimum, 50 uses."

With more than one store on the account, say which one — the tools require it explicitly so nothing gets written to the wrong store.

What it does

⚠️ Not validated against the live API. The other thirteen were run end to end against a real store — creating a product, changing a price, writing stock, issuing a coupon — and their field names came out of that process corrected. These two need an existing order, and the test store had none. The endpoints are right; the request body comes from the documentation, which turned out to be missing at least one required field in every one of the other five writes. Expect a 422 on first call — the message will name the missing field.

What it deliberately does not do

It does not cancel orders, refund purchases, or switch payment gateways. Not a feature behind an environment variable: the code does not exist. These are the irreversible operations in the API, and neither Claude Desktop nor claude.ai supports elicitation — meaning the server has no way to genuinely ask for confirmation. Absence is the only guarantee that doesn't depend on someone paying attention.

The ban is enforced in two places, both covered by tests: on the status alias (tools/write.ts) and at the seam every request passes through (yampi.ts). Rationale in docs/adr/0002.

Order tracking is also out: Yampi caps that route at 3 requests per hour, which makes the tool useless in practice — two calls and the agent is stuck for 20 minutes.

Your credentials

• Stored encrypted (AES-GCM) in the OAuth grant props, inside your KV.
• The key encrypting them is wrapped by a key derived from the access token, and KV only holds the token's hash. A KV leak alone does not open the credentials.
• Claude never receives them: it only ever sees an opaque token.
• Revoking means deleting the grant — other connections keep working.

/authorize is public and validates credentials, which technically makes it an oracle for testing stolen keys. Hence the limit of 5 attempts per IP per minute.

To restrict the instance to specific stores:

npx wrangler secret put ALLOWED_STORES   # e.g. my-store,other-store

API limits

Yampi limits per route per minute: 30 req/min on products and SKUs, 120 on order reads, 30 on writes, 60 in general. The server uses include= to pull relationships in a single call instead of N+1, reads X-RateLimit-Remaining off every response, and warns the model when the quota is running out — rather than letting it find out through a 429.

When something goes wrong

403 on everything, reads included. The store is active: false in the Yampi dashboard. Inactive stores reject every route. Reactivate it, then reconnect the connector.

422 on a write. The message names the exact field Yampi rejected — the server forwards the whole errors object. Claude usually corrects itself on the next attempt.

"Grant without credential". The grant lost its props. Remove the connector and add it again.

Switching credentials. Just reconnect: a new grant replaces the old one. To cut access without reconnecting, delete the KV namespace.

A store is missing from the list. Either it's inactive, or the credential doesn't reach it. Run describe_store to see what the server can see.

Yampi API quirks

Found by testing against the live API. All of them can burn hours, and none are clear from the documentation:

• Filters need array syntax. ?status_id=4 is silently ignored and returns the entire dataset; ?status_id[]=4 filters. Same for active[]. A filter that doesn't filter is worse than no filter: the agent summarizes 55,000 orders believing it saw July's.
• Dates use a bespoke format: ?date=created_at:2026-06-01|2026-06-30. Anything else returns 500 or is ignored.
• filters[...] does not filter. It only switches the response to scroll_id pagination.
• /auth/me is POST, not GET, and returns every store on the credential — because the credential belongs to the user, not the store.
• Order include has a closed enum: items, customer, marketplace, status, statuses, shipping_address, promocode, transactions, comments, files, discounts, seller, labels. There is no payments.
• GET responses are cached for 30 minutes on Yampi's side. In an agent context that lies: create a product, ask to read it back, and you get the previous state. This server sends ?skipCache=true on every read.
• Stock is not a SKU field. quantity on a SKU is always null — including on the real SKUs of a live store. Stock lives in /logistics/stocks (the stock location) joined to the SKU at /catalog/skus/{id}/stocks. And stock_id is not the id from /logistics/warehouses, which is a different resource entirely.
• Coupon discount_type accepts only p or v, not percentage/fixed.
• Coupon dates require Y-m-d H:i:s. Date alone returns 422.
• PUT /catalog/skus/{id} requires product_id and price_cost even for a partial update.
• Creating a product requires simple, brand_id and skus.*.blocked_sale, none of them obvious.
• A store with active: false returns 403 on everything, reads included. This server filters those stores out at connect time, so the model is never offered an option that can only fail.
• 422 responses carry an errors object naming the exact field that failed. Worth forwarding to the model instead of showing only the status code — it's what lets it correct itself.

Development

npm test              # 32 unit tests, no network
npm run typecheck
npm run dev           # wrangler dev

Testing against your own store

The unit suite uses a fake fetch and proves the server's logic. It cannot notice Yampi changing an endpoint, a field name or a filter syntax — and that happened repeatedly while this project was built. That other half is covered by an integration suite that hits the live API, read-only, creating and changing nothing:

cp .env.example .env    # fill in the alias and credentials of YOUR store
npm run test:integration

It checks that store discovery works, that status aliases exist, that filtering by status actually filters, that the date format is accepted, that include expands relationships, and that quota headers arrive. If one fails, the API changed and the server will start lying before it starts breaking.

The architecture has one rule: no tool speaks HTTP. Everything goes through src/yampi.ts. That's what makes the "does not reach the banned routes" promise auditable — the entire surface fits in one file.

Project vocabulary in CONTEXT.md. Decisions in docs/adr/.

Known limitations

• No order tracking (Yampi's 3 req/h cap makes it unusable).
• No banners, free shipping rules, progressive discounts or combos.
• advance_order_status and add_order_comment were never run against the live API.
• Stock is written to the store's first registered stock location. Anyone using multiple locations needs to adjust defaultStockId() in src/tools/write.ts.

Contributing

Pull requests are welcome. Fork it, open a PR against main, and CI runs typecheck and the unit tests. For anything larger than a bug fix, open an issue first.

One thing will not be merged regardless of patch quality: anything that cancels an order, refunds a purchase, or switches payment gateway, including indirect routes. That absence is the point of the project — reasoning in ADR 0002.

Details in CONTRIBUTING.md. Found a security issue? Do not open a public issue — see SECURITY.md.

License

MIT — see LICENSE.

The Yampi logo in assets/ is Yampi's trademark, used here only to identify which platform this server talks to. It is not covered by the MIT license and this project is not affiliated with or endorsed by Yampi.