In pycharm you have ctrl-q (or ctrl-j on a mac) for a quick-doc of the function under the cursor.

If Pycharm isn't giving you good suggestions, that's because it can't figure out what you're looking at. Python is duck typed. What a function takes or returns could be any type. But maybe you already know what it is. Pycharm's suggestions get better if you add type annotations for your functions or variables. Use Alt+Enter when your cursor is on a function or variable declaration to add type hints.

You can also use F1 to get help for the item under the cursor and you can Ctrl+click on a variable to jump to where it was defined.

In PyCharm you can select a function and press Alt+Shift+F7 to run a usage search. It's also available under "Edit → Find → Find Usages". It looks like it's more intelligent than a text search.

Using static analysis to find where a function is called from is difficult in general in Python because it uses dynamic binding and has a lot of introspection so it's very easy to get false positives miss usages. In the case of module-level functions I think a good solution is to always use module.function to call the function and never do a from module import function. That way you can do a text search for 'module.function'. Python style guides generally recommend that you import functions etc. in this way so I think this is generally accepted good practice.

Finding method calls is of course much harder. One of the things I like about developing in Java and C# is being able to find all usages of a method by static analysis.

In PyCharm:

Type the name of the function with the brackets (), and then place your cursor inside the brackets and type Ctrl + P; This will show your the parameters for the function.

Here is a short gif showing this:

In VSCode

Vscode uses the same keyboard shortcut as IntelliJ (and by extension, Pycharm). If the shortcut does not work, you can install the key bindings extension here

Example:

In a REPL

Open a python repl and type:

help (object)

Where object can be the name of a function or class, or any object as the name suggests.

Ex:

➜ python                                 
Python 3.7.1 (default, Dec  1 2018, 03:00:51) 
[GCC 7.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> help(sum)

Help on built-in function sum in module builtins:

sum(iterable, start=0, /) Return the sum of a 'start' value (default: 0) plus an iterable of numbers

When the iterable is empty, return the start value.
This function is intended specifically for use with numeric values and may
reject non-numeric types.

>>> def f():
...     return 3
... 
>>> help(f)

Help on function f in module __main__:

f()

>>>

The help page pops up and you can read any documentation associated with the object.

I found that I can make the Project window display the classes and methods (and functions outside classes) like this:

1. Select the Project (not Project Files) option in the leftmost dropdown.
2. Select "Show Members" in the "tools" (gear icon) dropdown.

The "Show Members" name threw me off because I'm not accustomed to thinking of files having "members." It does the job, though.