Compare prepaid travel eSIM plans by destination, data and trip length across 30+ providers, and plan multi-country trips.
ChatGPT is OpenAI's assistant. It can add custom MCP servers as plugins, which lets it call your tools from a conversation.
This guide connects MyBestSim MCP to ChatGPT through MewCP, so ChatGPT can use MyBestSim MCP's 4 tools, like search_esim_plans, plan_trip_esim and get_destination_overview.
MyBestSim MCP needs no credentials, but every call still runs through MewCP: scoped, checked and logged like any other.
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MyBestSim MCP works the same way in every client below. Pick yours for its own guide.
Free to start.
Scope access to the exact MyBestSim MCP tools and accounts you allow, work and personal side by side. Anything outside that scope is refused at call time, even when the model asks for it.
Each call is logged: what ran, on which account, and whether it worked. Failures come back structured, so the agent knows whether to retry instead of guessing.
Every app sits behind one secure MCP URL, and there is no server for you to deploy or keep running. Add an integration in the dashboard and it is live on the next call, with no config to change and no new credentials to wire up. Tools load only when a task needs them, so your agent stays fast and focused however many apps you connect.
In ChatGPT, open Plugins and choose Add custom MCP.
Name it "mewcp" and paste the server URL.
Click Connect. A sign-in window opens; sign in to MewCP and approve access. No API key needed.
Start a new chat and ask: "List the tools you can use from MewCP." You should see your connected apps.
Use this when someone is choosing a travel eSIM or needs mobile data abroad for a given country or region, e.g. "cheapest eSIM for Japan", "10 GB for two weeks in Europe", "unlimited data in the USA". Returns a shortlist (up to 10, at most 2 per provider) from the MyBestSim comparator: data allowance, validity, price in the traveller's currency (pass currency; also USD and EUR), 5G/hotspot/calls/SMS, and the link to the full comparison page on mybestsim.com where the traveller buys from the provider. Pass durationDays and dataGb (or dataNeed) whenever the traveller mentions trip length or usage, and ask for them when unknown: without them a 7-day trip with standard use (0.7 GB/day) is assumed and reported in "assumptions"; with dataGb but no durationDays, plans valid for fewer than 7 days are excluded. For a trip through several countries or regions, call plan_trip_esim with every stage instead of searching each country. Prepaid travel eSIMs only: not home mobile contracts, physical SIM cards or a carrier's roaming pass.
Use this when one trip visits SEVERAL countries or regions, e.g. "Japan then China", "two weeks in France, Italy and Spain", "Thailand, Vietnam and Cambodia in March". Pass EVERY stage in travel order, with the days spent in each when known (or totalDurationDays), and the data need. Compares, at the real total price, every way to cover the trip: (a) one eSIM for every stage (regional or worldwide plan; coverage is checked country by country against the MyBestSim catalogue, never guessed from a plan name), (b) one plan per stage, and combinations (a regional plan for some stages, other plans for the rest; several regional plans). A plan is only proposed for stages it covers, for their whole duration and data need. Recommends the cheapest total; prefers fewer eSIMs unless installing more saves at least $2 per extra eSIM, and says so. Gives the reason, the number of eSIMs, total price, data and validity, and links to the MyBestSim pages where the traveller buys. List the countries themselves as stages: a region stage (Europe, Asia…) only matches plans listed on that region page. Ask how long they stay and how much data they use when they have not said: without it a 7-day trip with standard use is assumed and reported in "assumptions". Prepaid travel eSIMs only.
Use this when someone asks how much a travel eSIM costs in a country or region, what the average or typical price is, or how much choice there is, before comparing individual plans. Returns the number of plans and providers listed on the MyBestSim comparison page, typical prices computed over all of them (median price of standard packages: 1 GB/7 days, 5, 10 and 20 GB/30 days, unlimited 7 and 30 days; median price per GB), the cheapest plan, the best price per GB, the cheapest unlimited plan if any, the available validities, and the link to the comparison page. Pass currency when you know the traveller's.
Use this when someone wants the detail of one plan returned by search_esim_plans or get_destination_overview: coverage (number of countries, region), features, validity and price. Needs the planId and the destination it was found under.
