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docs: stop presenting the in-memory client as the way to connect (#3443)

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Max 2026-09-05 04:15:58 +01:00 • committed by GitHub
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18
docs/run/legacy-clients.md
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@ -16,15 +16,25 @@ So a legacy client is not something you build *for*. It is something that connec
## One handler, both eras
Here is a tool that has to ask the user something, and both eras of client calling it:
Here is a tool that has to ask the user something:
```python title="server.py" hl_lines="24 37-38"
```python title="server.py" hl_lines="21"
--8<-- "docs_src/legacy_clients/tutorial001.py"
```
`reserve` needs one thing the model didn't supply: how many copies. `Annotated[..., Resolve(ask_quantity)]` is how a tool declares that (**[Dependencies](../handlers/dependencies.md)** is that whole story). Nothing in `reserve` names a version, checks a capability, or branches.
The two clients are open **at the same time**, on the same `mcp` object. `mode="legacy"` runs the `initialize` handshake: the exact connection a pre-2026 client opens. The other one takes the default and lands on `2026-07-28`.
Serve it over HTTP, and here are both eras of client calling it:
```console
uv run mcp run server.py --transport streamable-http
```
```python title="client.py" hl_lines="14-15"
--8<-- "docs_src/legacy_clients/tutorial001_client.py"
```
The two clients are open **at the same time**, against the same running server. `mode="legacy"` runs the `initialize` handshake: the exact connection a pre-2026 client opens. The other one takes the default and lands on `2026-07-28`. Run `python client.py` from a second terminal:
```text
2025-11-25 {'result': "Reserved 2 of 'Dune'."}
@ -115,7 +125,7 @@ Two things about it matter more than what it does.
!!! check
Do the wrong thing. `reserve` is the exact tool that just served both clients. Deploy it with
`stateless_http=True`, connect the same two clients over HTTP, and call it from each.
`stateless_http=True`, connect the same two clients, and call it from each.
The modern client still gets `Reserved 2 of 'Dune'.` The modern leg didn't change.