The ModelBuiler Report view shows all the variables and tools in a model along with each element's value and other properties. To open the Report view first open the model in ModelBuilder, then click Model > Report. Each model is linked to its report view and closing the model will close the linked report view automatically.
The report is categorized into two sections, Variables and Processes.
Variables
The Variables section of the report view shows all the input and output variables in the model. A dark blue oval indicates a data element while a cyan blue oval indicates a non-data element such as a number, string, or other type. Model Parameters are indicated with the letter P.
Processes
The Processes section of the report view shows the list of all geoprocessing tools used in the model. A yellow rectangle indicates each geoprocessing tool. Each process has a section showing the parameters used with the tool, and the messages returned by the tool if it has been run.
- The Parameters section is a list of the tool parameters. Each parameter's data type, value, parameter type (required or optional) and direction (input or output) is displayed. Some of the tool parameters will likely be variables in the model, which will result in matching entries in the Parameters and Variables sections.
- The Messages section displays all tool messages including errors, warnings, and informative messages. This section only appears if the tool is in the Has Been Run state.
Filtering
A number of filtered Views are available in the report view toolbar. Use these filters to limit the report to only specific element types. 
- All—Shows all elements in the model.
- Inputs—Shows only the input variables in the model.
- Outputs—Shows only the output variables in the model.
- Parameters—Shows only the variables marked as model parameters.
- Tools—Shows only the Tools section of the report.
- Errors—Shows only the tools that have failed with an error.
AutoSync report
The AutoSync option 
can be toggled on and off using button on the model report toolbar. AutoSync allows model edits to be continuously updated in the report. The default for AutoSync is off, so if you wish to see recent model changes reflected in the report you must save the model or click the Refresh button 
.