The Tooling API is specifically designed to support the development lifecycle of Salesforce applications. It provides fine-grained access to metadata and allows for development-centric operations that are not available in other APIs. Its capabilities include executing Apex tests, retrieving test results, and querying for code coverage information. Therefore, for a custom Java application intended to display code coverage and test results, the Tooling API is the most precise and appropriate choice as it is built for this exact purpose.

1. Salesforce Developer Documentation

"Tooling API": "Use Tooling API to build custom development tools or apps for Lightning Platform. For example

use Tooling API to: ... Manage Apex classes and triggers ... Get code coverage information." This directly supports the use of Tooling API for the required task.

2. Salesforce Developer Documentation

"Which API Should I Use?": This guide differentiates the APIs

stating

"Use Tooling API to build custom development tools for the Salesforce platform... It provides a SOAP and REST interface that allows you to access finer-grained pieces of metadata

such as individual Apex classes." This positions it as the correct tool for development-focused tasks over the bulk-oriented Metadata API.

3. Salesforce Developer Documentation

"Tooling API Objects": The existence of specific objects within the Tooling API

such as ApexCodeCoverageAggregate

ApexTestResult

and ApexTestQueueItem

confirms its role in managing and reporting on Apex testing and coverage. These objects are accessible via the Tooling API to retrieve the exact information required by the scenario.