# List and inspect apps

## Goal

Find out which PlayMolecule apps are installed, what each one does, and what parameters it accepts.

## Minimal example

```python
from playmolecule import describe_apps

describe_apps()
```

Prints each app's qualified import path and one-line description.

## Get the data as a dict

```python
apps = describe_apps(as_dict=True)
for path, info in apps.items():
    print(path, "—", info["description"])
```

The keys are fully qualified import paths (`playmolecule.apps.<name>.<version>.<function>`); the values currently expose only `description`. Use this when you need to drive a UI or a config file rather than print to a terminal.

## Inspect one app

Once imported, each app is a normal Python function with a real signature and docstring:

```python
from playmolecule.apps import proteinprepare

help(proteinprepare)              # parameters + outputs + examples
```

In IPython, `proteinprepare?` is equivalent. The docstring lists every parameter, its type, default, and description, plus the outputs the app writes and any example calls — everything you need to call the app correctly.

## See available versions

The versioned submodules live under the app's namespace:

```python
import playmolecule.apps.proteinprepare as pp
[name for name in dir(pp) if name.startswith("v")]   # ['v1', 'v2', ...]
```

The bare `proteinprepare` symbol aliases the latest version; everything else is at `pp.v1`, `pp.v2`, etc. See [Select an app version](select-an-app-version.md).

## Gotchas

- `describe_apps` only sees apps that loaded successfully at import time. If `PM_REGISTRIES` is unreachable (network down, wrong credentials) the function returns nothing — check the `playmolecule` logger output, or set `PM_LOG_LEVEL=DEBUG` to see why.
- A custom app whose manifest fails to parse is silently skipped at import time and logged as an error. `describe_apps` won't list it; check the import-time log to spot the problem.
- The descriptions you see are the first line of each app function's docstring. If you maintain an app, keep the first line tight.

## See also

- {py:func}`~playmolecule.describe_apps`
- [Select an app version](select-an-app-version.md)
- [Apps and manifests](../explanation/apps-and-manifests.md)