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Python lint: Ruff rules for pylint and code complexity#525

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Merged
felixweinberger merged 1 commit into from
Sep 5, 2025
Merged

Python lint: Ruff rules for pylint and code complexity #525

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26 changes: 22 additions & 4 deletions pyproject.toml
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Original file line numberDiff line numberDiff line change
Expand Up@@ -102,18 +102,36 @@ executionEnvironments = [
{ root = "examples/servers", reportUnusedFunction = false },
]

[tool.ruff.lint]
select = ["C4", "E", "F", "I", "PERF", "UP"]
ignore = ["PERF203"]

[tool.ruff]
line-length = 120
target-version = "py310"
extend-exclude = ["README.md"]

[tool.ruff.lint]
select = [
"C4", # flake8-comprehensions
"C90", # mccabe
"E", # pycodestyle
"F", # pyflakes
"I", # isort
"PERF", # Perflint
"PL", # Pylint
"UP", # pyupgrade
]
ignore = ["PERF203", "PLC0415", "PLR0402"]

@felixweinbergerfelixweinbergerSep 5, 2025

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"PLC0415" and "PLR0402" are newly added.

I'm assuming that's because we've added to the selection of tools above causing new lint errors to appear that we previously were ignoring by omission?

If so I'm OK with this trade-off in the short term to have a bit more manageable complexity.

mccabe.max-complexity = 24 # Default is 10

[tool.ruff.lint.per-file-ignores]
"__init__.py" = ["F401"]
"tests/server/fastmcp/test_func_metadata.py" = ["E501"]
"tests/shared/test_progress_notifications.py" = ["PLW0603"]

@felixweinbergerfelixweinbergerSep 5, 2025

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Not my favorite solution, but assuming the same thing applies as above - we have this code already, we were just ignoring it by omission.

PLW0603


[tool.ruff.lint.pylint]
allow-magic-value-types = ["bytes", "float", "int", "str"]
max-args = 23 # Default is 5
max-branches = 23 # Default is 12
max-returns = 13 # Default is 6
max-statements = 102 # Default is 50

[tool.uv.workspace]
members = ["examples/servers/*", "examples/snippets"]
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5 changes: 2 additions & 3 deletions src/mcp/server/fastmcp/server.py
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Expand Up@@ -182,9 +182,8 @@ def __init__(
raise ValueError("Cannot specify both auth_server_provider and token_verifier")
if not auth_server_provider and not token_verifier:
raise ValueError("Must specify either auth_server_provider or token_verifier when auth is enabled")
else:
if auth_server_provider or token_verifier:
raise ValueError("Cannot specify auth_server_provider or token_verifier without auth settings")
elif auth_server_provider or token_verifier:
raise ValueError("Cannot specify auth_server_provider or token_verifier without auth settings")

self._auth_server_provider = auth_server_provider
self._token_verifier = token_verifier
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6 changes: 3 additions & 3 deletions src/mcp/server/fastmcp/utilities/func_metadata.py
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Expand Up@@ -139,14 +139,14 @@ def pre_parse_json(self, data: dict[str, Any]) -> dict[str, Any]:
if field_info.alias:
key_to_field_info[field_info.alias] = field_info

for data_keyin data.keys():
for data_key, data_value in data.items():
if data_key not in key_to_field_info:
continue

field_info = key_to_field_info[data_key]
if isinstance(data[data_key], str) and field_info.annotation is not str:
if isinstance(data_value, str) and field_info.annotation is not str:
try:
pre_parsed = json.loads(data[data_key])
pre_parsed = json.loads(data_value)
except json.JSONDecodeError:
continue # Not JSON - skip
if isinstance(pre_parsed, str | int | float):
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1 change: 0 additions & 1 deletion src/mcp/server/lowlevel/server.py
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Expand Up@@ -85,7 +85,6 @@ async def main():
from mcp.server.lowlevel.helper_types import ReadResourceContents
from mcp.server.models import InitializationOptions
from mcp.server.session import ServerSession
from mcp.server.stdio import stdio_server as stdio_server
from mcp.shared.context import RequestContext
from mcp.shared.exceptions import McpError
from mcp.shared.message import ServerMessageMetadata, SessionMessage
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21 changes: 10 additions & 11 deletions src/mcp/server/streamable_http.py
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Expand Up@@ -838,17 +838,16 @@ async def message_router():
# If this response is for an existing request stream,
# send it there
target_request_id = response_id
else:
# Extract related_request_id from meta if it exists
if (
session_message.metadata is not None
and isinstance(
session_message.metadata,
ServerMessageMetadata,
)
and session_message.metadata.related_request_id is not None
):
target_request_id = str(session_message.metadata.related_request_id)
# Extract related_request_id from meta if it exists
elif (
session_message.metadata is not None
and isinstance(
session_message.metadata,
ServerMessageMetadata,
)
and session_message.metadata.related_request_id is not None
):
target_request_id = str(session_message.metadata.related_request_id)

request_stream_id = target_request_id if target_request_id is not None else GET_STREAM_KEY

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