# MCP Python SDK v2.0.0b2

- Product: MCP Python SDK (https://whatsnew.fyi/product/mcp-python-sdk)
- Vendor: Anthropic
- Date: 2026-07-14
- Version: v2.0.0b2
- Original notes: https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.0.0b2
- Permalink: https://whatsnew.fyi/product/mcp-python-sdk/releases/v2.0.0b2
- Labels: Pre-release

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

---

- **changed** — Replace httpx and httpx-sse with httpx2 (>=2.5.0) as the HTTP stack
- **changed** — TLS verification now uses the operating system trust store via truststore instead of certifi's bundle
- **changed** — Logger names changed from httpx to httpx2 and httpcore.* to httpcore2.*
- **changed** — SSE GET streams now send Accept header with application/json, text/event-stream instead of exactly text/event-stream
- **added** — Add client-side subscriptions/listen with context manager, async iteration, and typed events
- **added** — Request cancellation now works on 2026 transports by closing POST/SSE streams or sending notifications/cancelled over stdio
- **added** — Resolver dependency injection now supports Sample and ListRoots requests in addition to Elicit
- **fixed** — Tool-name validation now rejects names with a trailing newline

Second v2 beta. Pre-releases are opt-in only; `pip install mcp` still resolves to the stable 1.x line.

```bash
pip install mcp==2.0.0b2
#### or
uv add "mcp==2.0.0b2"
```

The [documentation](https://py.sdk.modelcontextprotocol.io/v2/) has the full tutorial and API reference, and the [migration guide](https://py.sdk.modelcontextprotocol.io/v2/migration/) covers coming from v1. Stable v2 is still targeted for 2026-07-28 alongside the spec release - keep pinning an exact version.

##### Highlights

###### httpx is replaced by httpx2 (#2972)

The SDK's HTTP stack now runs on [httpx2](https://pypi.org/project/httpx2/) (`>=2.5.0`), the next-generation httpx fork with SSE support built in, replacing `httpx` + `httpx-sse`. Most code needs no changes; if you pass your own `http_client` into a transport, change the import to `httpx2`. Runtime behavior that changes:

- TLS verification uses the operating system trust store (via `truststore`) instead of certifi's bundle. `SSL_CERT_FILE` / `SSL_CERT_DIR` are honored first.
- Loggers are renamed: `httpx` -> `httpx2`, `httpcore.*` -> `httpcore2.*` - update logging filters that match on those names.
- SSE GET streams send `Accept: application/json, text/event-stream` (previously exactly `text/event-stream`).

###### Client-side subscriptions/listen (#3047)

The client half of `subscriptions/listen` (SEP-2575), promised in the b1 notes: one context manager, `async for` consumption, typed events.

```python
async with client.listen(tools_list_changed=True, resource_subscriptions=["note://todo"]) as sub:
    print(sub.honored)  # the subset the server agreed to deliver
    async for event in sub:
        match event:
            case ToolsListChanged():
                tools = await client.list_tools()
            case ResourceUpdated(uri=uri):
                body = await client.read_resource(uri)
```

Entering waits for the server's acknowledgment, so `sub.honored` is always populated and pre-ack failures raise instead of degrading silently.

###### Request cancellation works on the 2026 transports (#3046)

Cancelling or timing out a client request now actually stops it: over streamable HTTP the request's own POST/SSE stream is closed (the spec's cancellation signal), and over stdio the client sends `notifications/cancelled`. Callers can also supply the request id for a call - the seam the listen driver builds on.

###### Resolvers can sample and list roots (#3049)

Resolver dependency injection now covers all three multi-round-trip request kinds (SEP-2322): a dependency can return `Sample(...)` or `ListRoots()` in addition to `Elicit(...)`, so a tool can ask the client's LLM or fetch its roots mid-call, on both protocol eras.

##### Notes

- Tool-name validation now rejects names with a trailing newline (#3076).
- The tasks extension is still in review and will ship in a later pre-release.
- If you install under uv's `exclude-newer` cooldown: `mcp` pins `mcp-types` to the exact same version, so exempt both packages - `exclude-newer-package = { mcp = false, mcp-types = false }`.

##### What's Changed
* De-flake conformance CI: solo re-verification, spawn-storm reduction, result artifacts by @maxisbey in https://github.com/modelcontextprotocol/python-sdk/pull/3043
* Harden the dual-era stream loop's era-lock and rejection semantics by @maxisbey in https://github.com/modelcontextprotocol/python-sdk/pull/3040
* docs: restructure into topical sections and add the four most-asked-for pages by @maxisbey in https://github.com/modelcontextprotocol/python-sdk/pull/3044
* docs: add a "What's new in v2" page by @maxisbey in https://github.com/modelcontextprotocol/python-sdk/pull/3054
* docs: modernize the site theme by @maxisbey in https://github.com/modelcontextprotocol/python-sdk/pull/3057
* docs: restructure the migration guide around topical groups with a navigation layer by @maxisbey in https://github.com/modelcontextprotocol/python-sdk/pull/

_[Truncated at 4000 characters — full notes: https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.0.0b2]_