@crossly/mcp

Model Context Protocol server for Crossly — the multi-marketplace crossposting platform for resellers.

Building your own integration in TypeScript instead of letting an AI drive? Use @crossly/sdk — same API, typed methods, no MCP host needed.

Exposes Crossly's public API as MCP tools so an AI agent (Claude Desktop, Cursor, Cline, Continue, etc.) can drive a seller's store end-to-end: list new items, crosspost across Poshmark / Mercari / eBay / Etsy / Depop / Grailed / Vinted / Whatnot / Vestiaire / Facebook / OfferUp / Shopify, edit prices, submit tracking, reply to buyer messages, accept/counter offers, run analytics, and configure automation rules.

Not on npm yet. @crossly/mcp is unreleased — the install command below will 404 until the first publish. To try it now, clone this repo and build from source. Star or watch to hear when it lands.

Install

No install — invoke via npx:

npx -y @crossly/mcp

The server reads two environment variables:

The PAT's scopes determine what the agent can do. A read-only token can only call list_* / get_* tools; a token without listings:write can't crosspost. Grant the minimum scopes the agent needs.

Related MCP server: TrySellr MCP Server

Claude Desktop config

Add to claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/claude_desktop_config.json; Windows: %APPDATA%\Claude\claude_desktop_config.json):

{
  "mcpServers": {
    "crossly": {
      "command": "npx",
      "args": ["-y", "@crossly/mcp"],
      "env": { "CROSSLY_PAT": "crossly_pat_live_..." }
    }
  }
}

Restart Claude Desktop. The Crossly tools appear under the hammer/MCP icon.

Cursor / Cline / Continue

Same shape — every MCP host accepts command + args + env. Point them at npx -y @crossly/mcp with CROSSLY_PAT in env.

Tools

Inventory

• list_inventory — List catalog items (filter by status / search).

• get_inventory_item — Get one item plus its per-platform listing rows.

• create_inventory_item — Add a new item to the catalog.

• update_inventory_item — Edit catalog defaults (does not push to live listings).

• archive_inventory_item — Soft-delete an item.

Listings

• list_listings — List live listings across marketplaces.

• get_listing — Get one listing with all per-platform rows / URLs.

• crosspost_listing — Publish an item to one or more marketplaces.

• update_listing — Push a price/title/image edit to live platforms.

• delist — Remove a listing from one or all platforms.

Orders

• list_orders — List orders (filter by status / platform).

• get_order — Get one order with buyer + shipping + tracking detail.

• submit_tracking — Mark shipped with a tracking number.

• issue_refund — Refund full or partial via the marketplace's API.

Sales

• list_sales — List unique sale events across marketplaces.

Inbox

• list_conversations — List buyer-message conversations.

• get_conversation — Get one conversation with its messages.

• reply_to_conversation — Send a text reply.

• respond_to_offer — Accept / counter / decline a buyer offer.

Analytics

• get_analytics_summary — Sales count, revenue, fees for the last N days.

Platform accounts

• list_platform_accounts — List connected marketplace accounts.

• add_platform_account — Add a new account slot (OAuth/extension login still required in the UI).

• remove_platform_account — Disconnect an account.

Automation

• list_automation_rules — List automation rules.

• create_automation_rule — Create a trigger-condition-action rule.

• delete_automation_rule — Remove a rule.

Webhooks

• list_webhooks — List registered webhook endpoints.

• register_webhook — Register a new endpoint (response includes the HMAC secret — shown once).

• delete_webhook — Remove an endpoint.

Idempotency

Every mutation tool accepts an optional idempotencyKey argument. If the agent might retry a call (transient network error, client crash, ambiguous timeout), pass a stable unique key — the Crossly API stores the first response and replays it for any retry within 24 hours. Strongly recommended for crosspost_listing, submit_tracking, issue_refund, and register_webhook.

Error handling

API errors are surfaced as MCP tool errors with the structured { error: { code, message } } envelope returned by the server. The agent receives a single text content block of the form:

Crossly API 403 (insufficient_scope): missing scope listings:write

This is intentional — the agent can read it, decide whether to retry or escalate, and explain it back to the user.

License

MIT