Open Ontologies is a Rust tool for planning, checking, applying, and rolling back changes to production ontologies, which are formal descriptions of concepts and their relationships. It helps ontology maintainers and reviewers inspect the consequences of edits and verify the resulting evidence with a Lean 4 checker. The catalogue includes add-ons such as skills, an instruction, a plugin, and an MCP integration for working with it.
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.
git clone --depth 1 https://github.com/fabio-rovai/open-ontologiesInstalling this writes the configuration, not the program: `./target/release/open-ontologies` has to be on your PATH already, or the server will not start.
Wrote 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/mcp/fabio-rovai/open-ontologies/open-ontologies)<a href="https://agentmods.dev/mcp/fabio-rovai/open-ontologies/open-ontologies"><img src="https://agentmods.dev/badge/mcp/fabio-rovai/open-ontologies/open-ontologies/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/mcp/fabio-rovai/open-ontologies/open-ontologies"><img src="https://agentmods.dev/badge/mcp/fabio-rovai/open-ontologies/open-ontologies.svg" alt="Reviewed on agentmods" width="80" height="20"></a>Grade A, and why
open-ontologies scanned grade A with 0 findings 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 1mo ago.
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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
{
"open-ontologies": {
"command": "./target/release/open-ontologies",
"args": [
"serve"
],
"env": {}
}
}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.
- 1mo ago First seen · 9 lines scan A d98307db6afb
open-ontologies is an MCP server published in the GitHub repository fabio-rovai/open-ontologies (1,345 stars, last pushed 2d ago), licensed MIT. Its token cost is not measured: an MCP server costs its tool schemas, not its config file. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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