coverage-analysis SKILL.md skillA
coverage-analysis from trailofbits/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add trailofbits/skills/coverage-analysis@git:20260826.3deb39ePins git:20260826.3deb39e in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- trailofbits/skills
- Path
plugins/testing-handbook-skills/skills/coverage-analysis/SKILL.md- Versions recorded
- 3
- Latest version
- git:20260826.3deb39e, committed Aug 26, 2026
- First version recorded
- Jan 14, 2026
- Size
- 21,004 bytes
- Repository stars
- 7,951
- License
- CC-BY-SA-4.0
Measures and interprets what a fuzzing campaign actually reaches, using llvm-cov, lcov, or a fuzzer's own coverage output. Covers baselining a new campaign, reading coverage reports, and turning uncovered regions into harness, seed, or dictionary work. Use when a fuzzer plateaus, when judging whether a harness is effective, after changing a harness, or when asking why some code is never reached.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Coverage Analysis Coverage analysis is essential for understanding which parts of your code are exercised during fuzzing. It helps identify fuzzing blockers like magic value checks and tracks the effectiveness of harness improvements over time. ## Overview Code coverage during fuzzing serves two critical purposes: 1. **Assessing harness effectiveness**: Understand which parts of your application are actually executed by your fuzzing harnesses 2. **Tracking fuzzing progress**: Monitor how coverage changes when updating harnesses, fuzzers, or the system under test (SUT) Coverage is a proxy for fuzzer capability and performance. While coverage [is not ideal for measuring fuzzer performance](https://arxiv.org/abs/1808.09700) in absolute terms, it reliably indicates whether your harness works effectively in a given setup. ### Key Concepts | Concept | Description | |---------|-------------| | **Coverage instrumentation** | Compiler flags that track which code paths are executed | | **Corpus coverage** | Coverage achieved by running all test cases in a fuzzing corpus | | **Magic value checks** | Hard-to-discover conditional checks that block fuzzer progress | …
Read the whole file at its exact version.
How to install
mdr add trailofbits/skills/coverage-analysis@sha256:9f71cfaffec44f15The line at the top of this page pins the label git:20260826.3deb39e, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_lliavkfnzgr3a2nr)
1 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 3 versions of this file, between Jan 14, 2026 and Aug 26, 2026, about one every 112 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260826.3deb39e latest | 2026-08-26 | 3deb39e | 21,004 B | A | view · diff |
| git:20260819.9e06dc6 | 2026-08-19 | 9e06dc6 | 20,741 B | A | view · diff |
| git:20260114.695119c | 2026-01-14 | 695119c | 20,696 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (21004 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
trailofbits/skills · 7,951 stars · license CC-BY-SA-4.0 · pushed 2026-10-28 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_lliavkfnzgr3a2nr GET https://markdownregistry.com/api/v1/resolve?ref=trailofbits/skills/coverage-analysis GET https://markdownregistry.com/api/v1/blob/9f71cfaffec44f159aa333924a25cdbe3eebd221cc7c0b0175fb93794d3ecacc
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
More from trailofbits/skills
Every file in trailofbits/skills