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Cypher eSIM MCP server

Which servers in the official MCP registry are Cypher eSIM's own, whether they answer, and what they offer. A program checked each of these, nobody copied them from a product page.

read 2026-10-23

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Whose server it is
  • Registry namecom.cypheresim/esimverified in the MCP registry

The registry name sits under cypheresim.com. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

When we asked itchecked 2026-10-23
  • Stateanswerschecked 2026-10-23
  • Tools9
  • Server calls itselfcypher-esim
  • Server version1.0.0
  • Protocol version2025-06-18

On 2026-10-23 the server answered initialize and tools/list without a sign-in. First answer in 166 ms.

Should an agent connect itNot proven either way yet
  • Its tools do every use case we checked: buy a regional data plan for a multi-country trip; top up an existing eSIM by ICCID with crypto.
  • Checked on 4 of the 7 days it takes to judge reliability.

Once connected

  • For "buy a regional data plan for a multi-country trip", the likely first call is search_destinations.
  • For "top up an existing eSIM by ICCID with crypto", the likely first call is list_topups.
  • create_order, cancel_order, create_topup change data without a sign-in: anyone with the address can call them.

Said by rules from the measurements above. The likely first call is a model's pick from the tool list; read its description before relying on it.

Measured dailydaily checks: 4, the first on 2026-10-23
  • INITE MCP scoreafter a weeka score needs 7 daily checks: 4 so far
  • What an agent can do with it2 of 2 use cases
  • Answeredmeasuring4 of the 7 daily checks it takes to print a share
  • Median first answer958 ms
  • Space in an agent's context≈ 1,661 tokensthe definitions of all its tools (9), which an agent carries on every turn
  • Tool definitionsA · 100 of 100
  • Typed results0 of 9 toolsdeclared outputSchema: results come typed, read once
  • Every tool passes all six checks.

What an agent can do with it

  • can do · buy a regional data plan for a multi-country trip
  • not sure · activate a data plan on arrival abroad
  • can do · top up an existing eSIM by ICCID with crypto

Each of the product's use cases, put to Jev against this server's tool list: can an agent do it with these tools?

Worth a look

  • Tools that change data, on a server that answers without a sign-in: create_order, cancel_order, create_topup

A program checks the server once a day: initialize and tools/list, no model. Tokens are the definitions' length at about four characters a token. The grade averages six checks of every tool's name, description, schema and annotations; it says how well the tools are described, not whether they work. The score weighs what was measured and nothing else: answering (30%), doing the product's job (25%), definitions (20%), context (10%) and use (15%). A part that was not measured is left out, and a hidden instruction caps the score at 40. The state of vendors' MCP servers: method and numbers →

Tools it offers9 tools · read 2026-10-23
  • search_destinations

    Find a country, region or "world" destination by name or ISO code. Returns destination codes for list_plans (country: ISO2 like "JP"; region: like "R-EUROPE"; world: "WORLD"), starting prices in USD, and how many data and phone-number…

  • list_plans

    List purchasable plans for a destination, cheapest first. type "data" = data-only eSIM: validity starts on first connection at the destination. type "number" = eSIM with a phone number, calls and SMS: validity starts at installation, so…

  • get_plan

    Full details of one plan: all covered countries, data, days, phone number (if any), install rules, when validity starts, and notes. Read the notes to the person before create_order.

  • list_payment_coins

    Coins and networks accepted for payment. Pass coin and network to create_order. Sending on a different network loses the funds.

  • create_order

    Create a crypto invoice for one new eSIM. Before calling, confirm the plan with the person and tell them when validity starts and the plan notes (number plans: validity starts at installation; Europe number is French +33; UK number plan…

  • get_order

    Order status: pending (waiting for payment), paid (issuing), delivered, expired, failed. When delivered, returns for each eSIM: QR code (also as an image), LPA activation code, ICCID, and one-tap iOS/Android install links. Call at most…

  • cancel_order

    Cancel an unpaid order the person decided not to pay. Do not cancel after the payment was sent.

  • list_topups

    Check whether an installed Cypher eSIM can be topped up and list the plans that can be added to it.

  • create_topup

    Create a crypto invoice that adds a data plan to an existing eSIM (no new QR, nothing to install). plan_id must come from list_topups for this ICCID. Payment and polling work exactly like create_order.

How to connect

Add the server to your MCP client config. Claude Desktop, Cursor and most other clients read this shape:

{
  "mcpServers": {
    "esim": {
      "type": "http",
      "url": "https://cypheresim.com/mcp"
    }
  }
}

Add it

Claude Code, in a terminal

claude mcp add --transport http cypheresim https://cypheresim.com/mcp

Add to CursorAdd to VS Code

claude.ai, ChatGPT and other clients: add https://cypheresim.com/mcp as a custom connector in the settings.

Each line is something a program found when it went looking: the registry entry, the server's own answer, a spec that parses. A missing line means we did not find it, not that it does not exist.