Meser10 MCP Server
Connect the Meser10 email & SMS platform to any MCP client (Claude, Cursor, or your own agent).
תיעוד בעברית, כולל התקנה מודרכת: https://www.meser10.co.il/features/mcp-server/
Listed in the official MCP Registry since 19 September 2026 as io.github.meser10/meser10-mcp
(v1.0.2, MIT). Verify independently, no account needed:
https://registry.modelcontextprotocol.io/v0/servers?search=meser10
Two Israeli email/SMS marketing platforms appear in the official registry. This is the only one of
the two published as open source and installable as a package; the other is a remote endpoint with
no repository and no package.
Tools are generated from the live WSDL. Nobody hand-writes 61 tool definitions here, which
means the server covers every API capability by construction and does not drift when the platform
ships a new operation.
Quick start
export MESER10_API_KEY=...
export MESER10_USER_ID=...
npx @meser10/mcp-server
MESER10_USER_ID is optional at start-up. 17 of the 61 operations are authenticated by the key
alone; the other 44 carry an explicit account number, and those fail with a clear message if it is
not set. Set it unless you know you only need the first group. The account number is an identifier,
not a secret - it is visible in the Meser10 UI.
Claude Desktop / Claude Code:
{
"mcpServers": {
"meser10": {
"command": "npx",
"args": ["-y", "@meser10/mcp-server"],
"env": { "MESER10_API_KEY": "...", "MESER10_USER_ID": "..." }
}
}
}
Safety model
The server starts read-only. Nothing that spends money, messages a real person, or deletes a
record is reachable until you opt in.
MESER10_MODE | Adds | Tools |
|---|
read (default) | the Get* family | 16 |
write | contacts, groups, campaign drafts | +27 |
send | delivers to real recipients, spends credit | +13 |
destructive | permanent deletes | +5 |
Two more guards:
MESER10_MAX_RECIPIENTS (default 100) refuses any single send that targets more addresses
than the cap. A model that misreads a prompt cannot mail your whole list.- Credentials are injected, never exposed.
oLogin and iUserID are stripped from every tool
schema and filled in by the server. A model cannot see, guess, or leak them. CLoginInfo does
accept UserName/Password, and this server deliberately never populates them - ApiKey only.
The one thing to know about errors
Every operation returns HTTP 200, including failures. Success lives in the Result field of
CCallResult, not in the status code. This server reads Result, throws on anything that is not
Success or PartialSuccess, and attaches a remedy:
LoginFailed: bad key - MESER10_API_KEY was rejected. Reissue the key in the Meser10 UI and restart.
PartialSuccess is surfaced as a warning rather than silent success, because it means some records
in a batch did not land.
Design notes
Legacy variants are hidden. The contract exposes five Ex/Ex2 families (15 operations for 5
capabilities). Offering all of them makes a model choose between near-identical tools and pick
wrong. The richest variant is exposed; the rest are hidden behind MESER10_EXPOSE_LEGACY=true.
Names are written for callers. GetGroupsList is what the platform calls it. list_groups is
what a developer reaches for. The underlying operation name is always in the description, so
nothing is hidden.
Hungarian prefixes become type hints. saGroups is an array of strings, eLang is an enum,
iUserID is an int. The generator uses that to produce better schemas and human titles.
Troubleshooting
LoginFailed on a key that worked five minutes ago. The platform blocks the calling IP
after a few failed authentications, and the block is long - measured at over three and three
quarter hours. It reports itself as Incorrect user name or password, which is indistinguishable
from a wrong key, so the instinct to reissue the key and retry makes it worse: the new key is
blocked too, because the block is not on the key.
If this happens: stop calling, wait, and do not put a retry loop around authentication. Never
retry an auth failure automatically - retrying is what creates the block, and on a shared server
it takes down every other integration sending from the same address.
NotEnoughPermissions. Either the key belongs to a different account than the
MESER10_USER_ID you set, or that account is real but out of your key's reach. An account number
the platform cannot resolve at all fails differently, as ApplicationError, so this message does
mean the number exists.
A tool returns a status and no data. Fixed in 1.0.0. Upgrade.
PartialSuccess. Part of a batch did not land. The server surfaces it as a warning rather
than silent success; check which records are missing before you retry the whole batch.
Support
support@meser10.co.il · 03-7440020 · Sunday to Thursday, 9:00-17:00 Israel time.
Include the operation name and the Result value you got back. Never include your API key, and
if one has been shared anywhere, reissue it.
Development
npm install && npm run build
npm test
The e2e suite runs a local stand-in for the platform, so it needs no credentials and sends nothing.
Status
Verified against the production endpoint on 2026-09-12, in read mode: authentication with ApiKey
only, tool listing, and four operations returning live data through the whole chain.
Also verified locally: WSDL parsing, schema generation, safety gate, envelope construction,
credential injection, error mapping, recipient cap, and the MCP protocol over stdio.
Write, send and delete operations are implemented and covered by tests against a stand-in, and
have deliberately never been executed against a live account by this project.