Unable to select the 'Description' field as list view filter criteria

Option 1: Create a Custom Text Field

As a workaround, System administrators can create a custom field to hold the data through which they are trying to filter.

• Create a custom Text field (can hold <255 characters on a single line) OR
• Create a custom Text Area Field (can hold <255 characters on multiple lines) OR
• Create any other type of custom field that would suit the type of data requested.

Note: The same is applicable to the field of data type Text Area (Rich).

Option 2: Use a Workflow Rule to Populate a Custom Field

This workaround involves populating the new custom field using a Workflow Rule or a Flow. A formula field is not an option as you can’t use long text area, encrypted, or Description fields in formulas.

In Enterprise Edition and above you have access to Workflow Rules. The below Workflow will update a custom field with the value of the Long Text Area field.

• Salesforce Classic: Setup | Create | Workflows & Approvals | Workflow Rules > Select New
• Lightning Experience: Setup | Platform Tools | Process Automation | Workflow Rules > Click New Rule

1. Select the Object.
2. Evaluation Criteria: Created and Every Time it's Edited
3. Rule Criteria: FORMULA

Use the following formula as the Rule Criteria:
(ISBLANK(PRIORVALUE(Insert Long Text Area field here)) && !ISBLANK(Insert Long Text field here)) || ISCHANGED(Insert Long Text Area field here)

4. Add Workflow Action: New Field Update
5. Field update will be on STEP 1 with a formula referencing the Long Text Area Field.

Option 3: Use Another Standard Field as a Proxy

Alternatively, you can put the data in another (otherwise unused) standard field, such as Title, which does appear in List View criteria.