Simfuse

Travel eSIMs for 200+ countries, as an MCP server. It lets an assistant browse destinations and data plans, read a plan's real terms (allowance, validity, fair-use policy, hotspot, the network it runs on), work out which countries a regional plan actually covers, price a whole multi-country trip against live retail prices, and open a checkout session at frozen prices. Payment, delivery and installation happen on simfuse.app; the server itself never charges anything.

• Endpoint: https://api.simfuse.app/agentic/mcp
• Transport: Streamable HTTP
• Auth: none. Every read tool is public.

Connect

Claude (claude.ai, Claude Desktop)

Open Customize > Connectors, click +, then Add custom connector, paste the endpoint URL and click Add. Leave the OAuth fields in Advanced settings empty, this server needs no credentials.

Claude connects from Anthropic's cloud rather than from your machine, so no local proxy is involved.

Claude Code

claude mcp add --transport http simfuse https://api.simfuse.app/agentic/mcp

Or in .mcp.json:

{
  "mcpServers": {
    "simfuse": {
      "type": "http",
      "url": "https://api.simfuse.app/agentic/mcp"
    }
  }
}

The "type" field is required. An entry with a url and no type is read as a stdio server and fails.

ChatGPT

Requires a Pro, Plus, Business, Enterprise or Education account on the web. Turn on Developer mode in Settings > Security and login (some builds put it under Settings > Apps & Connectors > Advanced), then go to chatgpt.com/plugins, press + and create a developer-mode app pointing at the endpoint URL. Choose No Authentication.

VS Code (Copilot agent mode)

In .vscode/mcp.json. Note the top-level key here is servers, not mcpServers:

{
  "servers": {
    "simfuse": {
      "type": "http",
      "url": "https://api.simfuse.app/agentic/mcp"
    }
  }
}

Cursor

In ~/.cursor/mcp.json (global) or .cursor/mcp.json (project):

{
  "mcpServers": {
    "simfuse": {
      "url": "https://api.simfuse.app/agentic/mcp"
    }
  }
}

Clients that only speak stdio

Bridge with mcp-remote:

{
  "mcpServers": {
    "simfuse": {
      "command": "npx",
      "args": ["mcp-remote", "https://api.simfuse.app/agentic/mcp", "--transport", "http-only"]
    }
  }
}

curl

curl -s https://api.simfuse.app/agentic/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"curl","version":"1.0"}}}'

curl -s https://api.simfuse.app/agentic/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/list"}'

Tools

Tool	What it does	Key parameters	Read-only
list-destinations	Every country on sale, with the cheapest plan price for each. Turns a place name into the two-letter code the other tools take.	search, currency, limit	yes
list-plans	The plans on sale for one destination, or a catalog-wide search narrowed by allowance, validity and price.	destination, min_data_amount_mb, max_data_amount_mb, min_validity_days, max_validity_days, min_price_cents, max_price_cents, currency, limit	yes
get-plan	One plan in full: allowance, validity, fair-use policy, hotspot and top-up support, network, price.	plan_id (required), currency	yes
get-plan-coverage	Every country a plan works in, plus any country of its own region it leaves out.	plan_id (required)	yes
plan-trip	Prices a whole trip. Compares one plan for the route against one plan per country against a mix, and returns the cheapest complete option with a reason.	stops (required), usage, start, currency	yes
create-checkout-session	Opens a checkout session at frozen prices and returns a bearer agent key. Charges nothing and reserves nothing.	items (required), currency, buyer_email, agent_name	no

Good to know:

• Every tool returns structuredContent matching the outputSchema it publishes in tools/list. Read that rather than parsing the text block, which is the same answer serialized for clients that cannot.
• Prices are integer minor units of the currency you asked for, so 1250 in EUR is 12.50 EUR. Pass currency explicitly so you always know what you are quoting.
• Data allowances are megabytes. 1 GB is 1024 MB.
• Plan ids are 26-character ULIDs and only ever come from a tool response. Never invent one, and look destination codes up rather than guessing.
• Quotes and sessions are offers, not reservations. The charged total is computed at checkout, and a session's prices hold only until its price_locked_until.

Worked example: a two-country trip

examples/plan-trip.mjs is a dependency-free Node script (Node 18+, using the built-in fetch) that runs initialize, tools/list and one plan-trip. Node was chosen because it needs no install step and no virtualenv, so the example is a single file you can run straight from a clone. It is read-only and never calls create-checkout-session.

node examples/plan-trip.mjs JP:7 KR:5

Real output, seven days in Japan then five in South Korea:

Server: SimFuse Storefront 1.0.0 (MCP 2025-06-18)
Tools:  plan-trip, list-destinations, list-plans, get-plan, get-plan-coverage, create-checkout-session

Planning: JP 7d -> KR 5d
  JP  2026-09-11 to 2026-09-18  needs about 5.5 GB
  KR  2026-09-18 to 2026-09-23  needs about 3.9 GB

Options compared:
* single      1 eSIM(s)  €13.99
  per_country 2 eSIM(s)  €20.68

Recommended: single
Why: One eSIM, SEA 10GB, covers all 2 stops for €13.99. It saves €6.69 over the next cheapest way to cover the route.

What to buy:
  - SEA 10GB
    10 GB, 30 days, €13.99  covers JP, KR
    plan id 01kvmtdhv2ygyshqzxah9zcwqh

Same trip on the site: https://simfuse.app/planner/?trip=2026-09-11.jp7r_kr5r

The underlying response also carries a checkout.items array shaped for create-checkout-session, per-stop data estimates, a warnings list naming any country not covered, and the full fair-use policy for each plan. Prices and plan ids change with the catalog, so your run will differ.

How it fits together

The server reads the same catalog, the same pricing rules and the same currency conversion as simfuse.app. A price quoted here is the price a person sees on the website in that currency at that moment. plan-trip runs the same recommendation engine the website's trip planner draws its comparison from, so the two surfaces cannot quote different answers.

There is no agent-only inventory and no agent-only pricing. Checkout sessions opened here go through the same checkout engine as a web or in-app purchase, and the eSIM is delivered by email once payment settles.

Plans are shown with their carrier and network type. Upstream supplier identities are not published, and the server says so rather than guessing if asked.

Links

• Website: https://simfuse.app/
• Agent documentation: https://simfuse.app/agent/
• Smithery listing: https://smithery.ai/servers/simfuse/esim-storefront
• mcp.so listing: https://mcp.so/servers/simfuse-esim-storefront
• Glama listing: https://glama.ai/mcp/connectors/app.simfuse.api/sim-fuse-e-sim-storefront
• Registry name: app.simfuse/esim-storefront
• server.json in this repo is the MCP registry manifest for the server.

Licence

The contents of this repository, the documentation and the example code, are released under the MIT licence. That licence covers this repository only. It does not cover the SimFuse service, the API, or the eSIM plans sold through it, which are governed by the terms published on simfuse.app.