## TL;DR

MCP clients differ in how they list tools, handle errors, and time out; testing one client is not enough.
A shared test script run against each client catches the quirks early.
Applies to any MCP server meant for public or multi-team use.

## The query

```text
testing MCP servers with multiple clients
```

## Use this when

- Your MCP server targets several clients.
- Clients differ in tool listing, errors, and timeouts.
- You want quirks caught before users hit them.

## Not for

- The server is for one specific client only (test that client deeply instead).
- You are still prototyping the tool surface (stabilize it first).
- The clients all use the same underlying library (one test run covers them).

## Steps

1. Write a test script that lists tools, calls each one, and checks the response shape.
   Expected output: A repeatable script covering the full tool surface.
2. Run it against each target client and record failures per client.
   Expected output: A per-client failure list showing exactly where behavior diverges.
3. Fix server-side where possible; document client quirks where you cannot.
   Expected output: A server that behaves consistently and a quirks doc for the rest.
4. Re-run the full matrix after every schema change.
   Expected output: A regression habit that keeps multi-client support honest.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_illZwFBFWMiqucn698ZjaA