fix(fetch): emit inclusive minimum/maximum for max_length (#1624)

src/fetch/src/mcp_server_fetch/server.py

@@ -169,8 +169,11 @@ class Fetch(BaseModel):
         Field(
             default=5000,
             description="Maximum number of characters to return.",
-            gt=0,
-            lt=1000000,
+            # ge/le rather than gt/lt: the inclusive bounds emit minimum/maximum,
+            # which every client accepts, while exclusiveMinimum/exclusiveMaximum
+            # are rejected by some (Gemini, #1624). Same range for an int.
+            ge=1,
+            le=999999,
         ),
     ]
     start_index: Annotated[

src/fetch/tests/test_protocol.py

@@ -107,7 +107,6 @@ async def test_server_version_is_the_sdk_version(web: FakeWeb) -> None:
 # --------------------------------------------------------------------------
 
 
-# KNOWN BUG #1624: pins current (wrong) behavior; the fix changes this assertion.
 async def test_list_tools_wire_shape(web: FakeWeb) -> None:
     async with connect() as (session, _):
         result = await session.list_tools()
@@ -129,13 +128,13 @@ async def test_list_tools_wire_shape(web: FakeWeb) -> None:
                 "title": "Url",
                 "type": "string",
             },
-            # #1624: pydantic's gt/lt emit the numeric (draft 6+) form of
-            # exclusiveMinimum/exclusiveMaximum, which some clients reject.
+            # #1624: inclusive minimum/maximum, never exclusiveMinimum/
+            # exclusiveMaximum, which some clients (Gemini) reject.
             "max_length": {
                 "default": 5000,
                 "description": "Maximum number of characters to return.",
-                "exclusiveMaximum": 1000000,
-                "exclusiveMinimum": 0,
+                "maximum": 999999,
+                "minimum": 1,
                 "title": "Max Length",
                 "type": "integer",
             },
@@ -184,7 +183,8 @@ async def test_call_with_only_url_applies_defaults(web: FakeWeb) -> None:
         ({}, "'url'"),
         ({"url": ""}, "''"),
         ({"url": 5}, "5"),
-        # #1624: the bounds come from exclusiveMinimum/exclusiveMaximum.
+        # #1624: the bounds are minimum 1 and maximum 999999, so the rejected
+        # values are the same as under the old exclusive 0 and 1000000.
         ({"url": PAGE, "max_length": 0}, "0"),
         ({"url": PAGE, "max_length": 1000000}, "1000000"),
         ({"url": PAGE, "start_index": -1}, "-1"),
@@ -205,6 +205,18 @@ async def test_schema_violations_are_rejected_by_the_sdk(
     assert web.requests == []
 
 
+@pytest.mark.parametrize("max_length", [1, 999999])
+async def test_max_length_bounds_are_inclusive(web: FakeWeb, max_length: int) -> None:
+    # #1624: the edges of the inclusive range pass both the SDK's schema check
+    # and Fetch's own validation, and the page is fetched.
+    web.add(ROBOTS, plain("", status=404))
+    web.add(PAGE, plain("hello"))
+    async with connect() as (session, _):
+        result = await call(session, {"url": PAGE, "max_length": max_length})
+    assert wire(result)["isError"] is False
+    assert web.urls() == [ROBOTS, PAGE]
+
+
 @pytest.mark.parametrize("url", ["not a url", "example.com/page", "http://"])
 async def test_invalid_url_is_rejected_by_pydantic(web: FakeWeb, url: str) -> None:
     # jsonschema does not check `format: uri`, so these reach Fetch(**arguments)