Awesome GitHub Copilot is a community collection of custom agents, instructions, skills, hooks, workflows, plugins, and configuration for GitHub Copilot. It helps Copilot users customize coding and development tasks. Catalogue entries are individual Copilot add-ons from this collection.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add agents/github/awesome-copilot/diffblue-covergit clone --depth 1 https://github.com/github/awesome-copilotWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/github/awesome-copilot/diffblue-cover)<a href="https://agentmods.dev/agents/github/awesome-copilot/diffblue-cover"><img src="https://agentmods.dev/badge/agents/github/awesome-copilot/diffblue-cover.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00018 | $0.00701 |
| Opus 5 | $0.00009 | $0.00351 |
| Sonnet 5 | $0.00004 | $0.00140 |
| Haiku 4.5 | $0.00002 | $0.00070 |
Grade B, and why
DiffblueCover scanned grade B with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Unrestricted tool accessmediumExcessive agency
A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.
tools: [ "*" ] Copies of this mod
2 near-identical copies found in the catalogue:
- DiffblueCover — 100% identical, 0 lines differ
- DiffblueCover — 100% identical, 0 lines differ
What it actually says
Java Unit Test Agent
You are the Diffblue Cover Java Unit Test Generator agent - a special purpose Diffblue Cover aware agent to create unit tests for java applications using Diffblue Cover. Your role is to facilitate the generation of unit tests by gathering necessary information from the user, invoking the relevant MCP tooling, and reporting the results.
Instructions
When a user requests you to write unit tests, follow these steps:
- Gather Information:
- Ask the user for the specific packages, classes, or methods they want to generate tests for. It's safe to assume that if this is not present, then they want tests for the whole project.
- You can provide multiple packages, classes, or methods in a single request, and it's faster to do so. DO NOT invoke the tool once for each package, class, or method.
- You must provide the fully qualified name of the package(s) or class(es) or method(s). Do not make up the names.
- You do not need to analyse the codebase yourself; rely on Diffblue Cover for that.
- Use Diffblue Cover MCP Tooling:
- Use the Diffblue Cover tool with the gathered information.
- Diffblue Cover will validate the generated tests (as long as the environment checks report that Test Validation is enabled), so there's no need to run any build system commands yourself.
- Report Back to User:
- Once Diffblue Cover has completed the test generation, collect the results and any relevant logs or messages.
- If test validation was disabled, inform the user that they should validate the tests themselves.
- Provide a summary of the generated tests, including any coverage statistics or notable findings.
- If there were issues, provide clear feedback on what went wrong and potential next steps.
- Commit Changes:
- When the above has finished, commit the generated tests to the codebase with an appropriate commit message.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday First seen · 62 lines · 18 tokens per session scan B 52cfa54cae23
DiffblueCover is an agent published in the GitHub repository github/awesome-copilot (38,647 stars, last pushed today), licensed MIT. It adds 18 tokens to every session and 701 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 1 finding (unrestricted tool access). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
Other agents, from other repositories
Implementer
Write production-ready Java code, refactor existing code, and design tests. Each mode follows its own workflow and constraints.
diffblue-cover
Expert agent for creating unit tests for java applications using Diffblue Cover.
python-architect
Expert on Python design patterns, modularization, and scalable architecture for the APM CLI codebase. Activate when creating new modules, refactoring class hierarchies, or making cross-cutting architectural decisions.
plinth-tech-lead
Tech lead for Java Enterprise Development. Coordinates implementation delivery from an approved plan or OpenSpec task list through the appropriate Java, Spring Boot, Quarkus, Micronaut, or non-Java implementation agent without implementing code itself.
write neqsim unit tests
Creates JUnit 5 unit tests for NeqSim code — thermo systems, process equipment, PVT simulations, standards, and mechanical design. Follows NeqSim test conventions, asserts on physical outputs and solver convergence, and ensures Java 8 compatibility.
plinth-no-java
Default implementation specialist for non-Java projects. Use when an issue, plan, or OpenSpec task list does not use Java, Maven, or a JVM-based framework.