Security

Filtered Before You Install: Security Scans for Agent Skills.

Nous Research added NVIDIA SkillEvaluator's static checks to its agent harness Hermes, scanning for PII, secret leaks, Unicode smuggling, and license issues right before a skill is installed, and applied it first to 11 of its own bundled skills. According to NVIDIA's official benchmark, verified skills also raise performance metrics such as correctness by 41 points and effectiveness by 39.

· Huuush

Filtered Before You Install: Security Scans for Agent Skills

Key takeaways

  1. 1Nous Research added NVIDIA SkillEvaluator's static checks to its agent harness Hermes, scanning for PII, secret leaks, Unicode smuggling, and license issues before a skill installation is confirmed.
  2. 2Nous Research said it applied the check to its own bundled skills first and improved 11. The check is advisory and doesn't block installation, and findings are shown with file and line numbers before you confirm.
  3. 3According to NVIDIA's official benchmark (more than 300 verified skills, across the Claude Code and OpenAI Codex harnesses), verified skills also raise performance metrics, such as correctness from 46 to 87 and effectiveness from 39 to 78.
Diagram of a three-stage inspection pipeline on a dark background, with each stage connected by arrows

Before you install a skill on your agent, it now gets inspected first. Nous Research said on its official X account on August 20 that it has attached NVIDIA's SkillEvaluator to its agent harness Hermes.

From PII to Unicode smuggling

In its official announcement, Nous Research said that "when installing a skill, Hermes uses NVIDIA SkillEvaluator to check for PII, secret leaks, Unicode smuggling, license, and security issues before you hit confirm."

This check doesn't block installation. According to Hermes's official documentation, the Tier 1 check is deterministic and works without an API key, and findings are shown with file names and line numbers before you confirm installation, but the installation itself still goes ahead. Items that look like real credentials (private keys, cloud access keys, tokens, and connection strings containing credentials) are highlighted in red so the user can decide for themselves whether to install.

Agent skills are downloaded and installed freely from a marketplace, so in effect files with code-execution permissions were being brought in with no real verification. An automatic pre-install scan means this distribution structure has a minimal gatekeeper for the first time.

Why did 11 of its own skills get flagged first?

Nous Research applied this check first to the bundled skills it distributes itself. It said it found parts needing improvement in 11 skills and fixed them. Which items were real security risks and which were simple false positives hasn't been disclosed officially, which is something we can't officially confirm.

That its own content got caught by its own check shows two things at once: the check actually catches something, and even officially distributed skills had been circulating without this kind of static verification.

The effect of skills in numbers: +41 points

In a separate official technical blog post, NVIDIA published results from benchmarking more than 300 verified skills across more than 30 products on two harnesses, Claude Code and OpenAI Codex. It compared with and without skills on the same tasks, the same model, and the same settings.

MetricWithout skillsWith skillsChange
Correctness4687+41
Effectiveness3978+39
Discoverability4282+40
Efficiency4378+35
Security9798+1

Only the security metric stays nearly flat (97 to 98). That means skills that passed NVIDIA's verification had few security problems to begin with, and the SkillEvaluator integration Nous Research added is closer to a safeguard for the opposite side: reducing the risk from ordinary skills that circulate without being verified.

It checks, but it doesn't block installation

The feature's core limitation is clear. Even when results come back, it doesn't force the installation to stop. The final decision is still up to the user. One comment on NVIDIA AI's official account suggested "building a registry of scanned skills so enterprises can audit them," and Nous Research responded by pointing to its own Skills Hub. How systematized that hub is, separate from this SkillEvaluator integration, can't be confirmed from this announcement alone.

If your team installs and distributes agent skills internally, it's safer to first look into what this kind of check misses rather than the mere fact that it exists. Tier 1 is a static check, so malicious behavior that only shows up at runtime would only be caught by going through Tier 3 (sandboxed real-use evaluation).

Frequently asked questions

Does NVIDIA SkillEvaluator block skill installation?
No. The Tier 1 static check is advisory. If PII, secrets, Unicode smuggling, or license issues are found, they're shown with file names and line numbers before you confirm installation, but installation itself isn't blocked. Items that look like real credentials (private keys, cloud access keys, tokens, and so on) are highlighted in red for the user to review and decide.
Where did Nous Research apply this check first?
It said on its official X account that it applied the check first to the bundled skills it distributes itself and improved 11. Which items were real security problems and which were false positives hasn't been disclosed.
What do SkillEvaluator's three tiers of checks each do?
Tier 1 (safety and structure) statically performs schema and frontmatter validation, quality scoring, security scans for prompt injection and data exfiltration, secret and PII detection, license checks, and script linting. Tier 2 (differentiation) uses embedding similarity to find duplicate guidance between skills and the extent of overlap across the whole catalog. Tier 3 (real-use evaluation) directly compares agent performance before and after applying a skill in an isolated sandbox.
How much does using verified skills actually improve performance?
In NVIDIA's official benchmark (more than 300 verified skills across more than 30 products, on the Claude Code and OpenAI Codex harnesses), correctness rose from 46 to 87, effectiveness from 39 to 78, discoverability from 42 to 82, and efficiency from 43 to 78. These figures are based on NVIDIA's own catalog of verified skills, though, and haven't been confirmed to apply equally to all third-party skills.

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