Diffblue Cover MCP Server
OfficialServer Configuration
Describes the environment variables required to run the server.
| Name | Required | Description | Default |
|---|---|---|---|
| DIFFBLUE_COVER_CLI | No | The location of the installed dcover command line | |
| DIFFBLUE_COVER_OPTIONS | No | Use these dcover options as well as those supplied by the LLM |
Instructions
Guidance the server publishes about itself, which clients place ahead of the tool catalog so the model reads it before choosing anything.
This server publishes no instructions, or was last inspected before Glama recorded them.
Capabilities
Features and capabilities supported by this server
Protocol revision2025-11-25
| Capability | Details |
|---|---|
| tools | {
"listChanged": true
} |
| prompts | {
"listChanged": false
} |
| resources | {
"subscribe": false,
"listChanged": false
} |
| experimental | {} |
Tools
Functions exposed to the LLM to take actions
| Name | Description |
|---|---|
| createA | Invoke Diffblue Cover to generate unit tests for Java code. This tool executes the dcover CLI to automatically generate JUnit tests for the specified Java classes, methods, or packages. It supports various configuration options to control the test generation process. Args: path: Path to the dcover executable. If not provided, searches system PATH and the DIFFBLUE_COVER_CLI environment variable. working_directory: Root directory of the Java project to test. Defaults to the current working directory. dcover_timeout: Maximum execution time in seconds. Defaults to 600. Set to None for no timeout (not recommended). entry_points: List of fully-qualified Java targets (packages, classes, or methods) to generate tests for. Examples: ['com.example.MyClass', 'com.example.MyClass.myMethod']. If None, tests entire project. args: Additional arguments to pass to dcover. Defaults to None. ctx: MCP server context for logging and progress reporting (auto-injected by FastMCP). Returns: dict: Execution result containing: - return_code (int): Exit code (0 for success) - status (str): "success" if completed without errors - output (str): Complete stdout/stderr from dcover - command (list[str]): The exact command that was executed - working_directory (Path): Directory where command was run Raises: ToolError: If dcover executable not found, command fails, or timeout exceeded. The error includes the partial output collected before failure. Note: If DIFFBLUE_COVER_OPTIONS environment variable is set, it overrides all option parameters (batch, skip_verification, etc.) except path, working_directory, timeout, and entry_points. |
| refactorA | Invoke Diffblue Cover to refactor the project (aliased as 'fix-build'). This tool executes the Args: path: Path to the dcover executable. If not provided, searches system PATH and the DIFFBLUE_COVER_CLI environment variable. working_directory: Root directory of the Java project to test. Defaults to the current working directory. dcover_timeout: Maximum execution time in seconds. Defaults to 600. Set to None for no timeout (not recommended). dry_run: If True, passes the '--dry-run' flag to check for readiness without applying changes. args: Additional arguments to pass to dcover. Defaults to None. ctx: MCP server context for logging and progress reporting (auto-injected by FastMCP). Returns: dict: Execution result containing: - return_code (int): Exit code (0 for success) - status (str): "success" if completed without errors - output (str): Complete stdout/stderr from dcover - command (list[str]): The exact command that was executed - working_directory (Path): Directory where command was run Raises: ToolError: If dcover executable not found, command fails, or timeout exceeded. The error includes the partial output collected before failure. |
| issuesA | Invoke Diffblue Cover to identify project issues. This tool executes the Args: path: Path to the dcover executable. If not provided, searches system PATH and the DIFFBLUE_COVER_CLI environment variable. working_directory: Root directory of the Java project to test. Defaults to the current working directory. dcover_timeout: Maximum execution time in seconds. Defaults to 600. Set to None for no timeout (not recommended). limit: Limit the number of issues to output. skip: Skip the first N issues from the report. prompt: If True, outputs a suggested prompt for each actionable issue. cover_json: Location of the JSON-formatted test-writing summary report. dry_run: If True, passes the '--dry-run' flag to check for readiness. args: Additional arguments to pass to dcover. Defaults to None. ctx: MCP server context for logging and progress reporting (auto-injected by FastMCP). Returns: dict: Execution result containing: - return_code (int): Exit code (0 for success) - status (str): "success" if completed without errors - output (str): Complete stdout/stderr from dcover - command (list[str]): The exact command that was executed - working_directory (Path): Directory where command was run Raises: ToolError: If dcover executable not found, command fails, or timeout exceeded. The error includes the partial output collected before failure. |
Prompts
Interactive templates invoked by user choice
| Name | Description |
|---|---|
| write tests | Provide system prompt for Java unit test writing guidance. Establishes LLM context as a Java unit testing expert to improve test generation quality and suggestions. Returns: list[dict]: System role message defining the assistant's expertise. |
Resources
Contextual data attached and managed by the client
| Name | Description |
|---|---|
| create_options | Provides the configuration options for creating tests with Diffblue Cover. |
TDQS
Scored across 3 tools
Each tool maps to a distinct dcover subcommand: create for test generation, refactor for build fixes, and issues for diagnosing problems. There is no meaningful overlap in their purposes, and the descriptions clearly differentiate them.
Two tools use imperative verbs (create, refactor) while the third uses a noun (issues), creating a slight inconsistency. However, the names are short, memorable, and directly correspond to CLI commands, so the deviation is minor.
Three tools is minimal but appropriate for a focused wrapper around the Diffblue Cover CLI. Each tool covers a real workflow stage, leaving little room for redundancy, though the server might feel slightly thin for broader use cases.
The tool surface covers the core workflow: diagnose issues, generate tests, and refactor/fix problems. Minor gaps exist, such as lack of explicit status or configuration tools, but these are not essential and can be worked around via the 'args' parameters.