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=...      # issued in the Meser10 UI
export MESER10_USER_ID=...      # your account number - optional, see below
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            # 43 unit tests + 12 end-to-end tests over real MCP stdio

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.