Max Isbey
1b74b06753
Cut comment and docstring volume roughly in half across src, tests, examples, and docs_src: removed comments that restate the adjacent code, leftover development narration, section banners, and self-evident Args/Returns blocks, and compressed the remaining docstrings to a Google-style summary line plus only the detail that earns its place. Kept (and tightened) the load-bearing content: Raises sections, deprecation and version-availability notes, spec/RFC/issue references, why-comments for non-obvious decisions, and all coverage pragmas. The generated mcp_types.v* wire modules are untouched.
119 lines
4.9 KiB
Python
119 lines
4.9 KiB
Python
"""`docs/advanced/deprecated.md`: the page's behavioural claims, executed against the live SDK.
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The chapter has no `docs_src/` example by design — a runnable one would teach exactly what
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the page tells readers not to build — so each test runs a claim the page states in prose,
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keeping the prose from drifting away from what the SDK does.
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"""
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import warnings
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import pytest
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from mcp_types import CreateMessageRequestParams, CreateMessageResult, SamplingMessage, TextContent
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from mcp import Client, MCPDeprecationWarning, MCPError
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from mcp.client import ClientRequestContext
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from mcp.server import MCPServer
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from mcp.server.mcpserver import Context
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from mcp.shared.exceptions import NoBackChannelError
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pytestmark = pytest.mark.anyio
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mcp = MCPServer("Deprecated")
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@mcp.tool()
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async def ask_model(prompt: str, ctx: Context) -> str:
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"""A tool still built on server-initiated sampling."""
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result = await ctx.session.create_message( # pyright: ignore[reportDeprecated]
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messages=[SamplingMessage(role="user", content=TextContent(type="text", text=prompt))],
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max_tokens=8,
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)
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return str(result.content)
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@mcp.tool()
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async def old_log(ctx: Context) -> str:
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"""A tool still built on protocol logging."""
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await ctx.info("hello") # pyright: ignore[reportDeprecated]
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return "ok"
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async def test_create_message_warns_and_then_raises_on_a_modern_connection() -> None:
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"""`@deprecated` warns the moment the method is called; only afterwards does the channel refuse the send."""
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async with Client(mcp) as client:
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with (
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pytest.warns(
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MCPDeprecationWarning,
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match=r"^The sampling capability is deprecated as of 2026-07-28 \(SEP-2577\)\.$",
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),
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pytest.raises(NoBackChannelError) as exc,
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):
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await client.call_tool("ask_model", {"prompt": "hi"})
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assert str(exc.value) == (
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"Cannot send 'sampling/createMessage': "
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"this transport context has no back-channel for server-initiated requests."
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)
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async def test_a_deprecated_feature_still_works_on_a_legacy_session() -> None:
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"""The deprecation is advisory: under mode='legacy' the same tool completes, with only the warning."""
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async def canned_sampling(context: ClientRequestContext, params: CreateMessageRequestParams) -> CreateMessageResult:
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return CreateMessageResult(
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role="assistant",
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content=TextContent(type="text", text="four"),
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model="canned",
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stop_reason="endTurn",
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)
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async with Client(mcp, mode="legacy", sampling_callback=canned_sampling) as client:
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with pytest.warns(MCPDeprecationWarning, match=r"The sampling capability is deprecated"):
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result = await client.call_tool("ask_model", {"prompt": "What is 2 + 2?"})
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assert not result.is_error
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[content] = result.content
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assert isinstance(content, TextContent)
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assert "four" in content.text
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async def test_send_ping_still_carries_the_deprecation_warning() -> None:
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"""`ping` is removed outright in 2026-07-28 (no deprecation window), yet the method is still decorated."""
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async with Client(mcp) as client:
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with (
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pytest.warns(
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MCPDeprecationWarning,
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match=r"^ping is removed as of 2026-07-28; the method only works under mode='legacy'\.$",
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),
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pytest.raises(MCPError, match="^Method not found$"),
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):
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await client.send_ping() # pyright: ignore[reportDeprecated]
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def test_mcp_deprecation_warning_is_a_user_warning() -> None:
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"""Deriving from `UserWarning` keeps the warning visible with no `-W` flag;
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Python's default filter hides `DeprecationWarning` outside `__main__`."""
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assert issubclass(MCPDeprecationWarning, UserWarning)
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assert not issubclass(MCPDeprecationWarning, DeprecationWarning)
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@pytest.mark.filterwarnings("error::mcp.MCPDeprecationWarning")
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async def test_error_filter_turns_the_deprecated_call_into_the_documented_tool_error() -> None:
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"""Under the error filter the warning is raised, wrapped, and surfaces as the tool error the page quotes."""
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async with Client(mcp) as client:
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result = await client.call_tool("old_log", {})
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assert result.is_error
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[content] = result.content
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assert isinstance(content, TextContent)
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assert content.text == (
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"Error executing tool old_log: The logging capability is deprecated as of 2026-07-28 (SEP-2577)."
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)
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async def test_filterwarnings_ignore_silences_the_whole_category() -> None:
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async with Client(mcp) as client:
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with warnings.catch_warnings(record=True) as caught:
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warnings.simplefilter("always")
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warnings.filterwarnings("ignore", category=MCPDeprecationWarning)
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result = await client.call_tool("old_log", {})
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assert not result.is_error
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assert not any(issubclass(w.category, MCPDeprecationWarning) for w in caught)
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