Semantica is an open-source infrastructure layer that turns enterprise data into structured context and knowledge graphs, where ontologies define meaning and graph reasoning connects facts and decisions. It is intended for AI systems and agents that need traceable, governed, and explainable context in high-stakes domains. The catalogue add-ons provide agent workflows, hooks, and plugins for operating Semantica.
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 skills add semantica-agi/semantica --skill ontologygit clone --depth 1 https://github.com/semantica-agi/semanticaWrote 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/skills/semantica-agi/semantica/ontology)<a href="https://agentmods.dev/skills/semantica-agi/semantica/ontology"><img src="https://agentmods.dev/badge/skills/semantica-agi/semantica/ontology/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/skills/semantica-agi/semantica/ontology"><img src="https://agentmods.dev/badge/skills/semantica-agi/semantica/ontology.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 5.1 | $0.00033 | $0.00540 |
| Opus 5.5 | $0.00013 | $0.00216 |
| Sonnet 5.5 | $0.00007 | $0.00108 |
| Haiku 4.5 | $0.00003 | $0.00054 |
Grade A, and why
ontology 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- ontology — 89% identical, 80 lines differ
How it starts
The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/semantica:ontology
Manage ontology definitions and validation. Usage: /semantica:ontology <task> [args]
Entry points:
OntologyEngine(authoring, export, alignments) andOntologyValidator(consistency checking).
concepts <scheme_uri>
List SKOS concepts in a vocabulary scheme.
from semantica.ontology import OntologyEngine
from semantica.triplet_store import TripletStore
store = TripletStore(backend="oxigraph") # needs semantica[tripletstore-oxigraph]
engine = OntologyEngine(store=store) # list_concepts/list_vocabularies need a
# configured store — raises ProcessingError without one
concepts = engine.list_concepts(scheme_uri)
vocabs = engine.list_vocabularies()
validate <ontology>
Check an ontology for consistency and satisfiability.
from semantica.ontology import OntologyValidator
validator = OntologyValidator(check_consistency=True, check_satisfiability=True)
result = validator.validate(ontology) # dict or path to an ontology file
# result.valid, result.errors, result.warnings
For SHACL shape validation of instance data use SHACLGenerator / SHACLValidationReport:
from semantica.ontology import SHACLGenerator
build <text|data>
Generate an ontology from unstructured text or structured records.
engine = OntologyEngine()
onto = engine.from_text(text) # LLM-assisted (needs an llm-* extra + API key)
onto = engine.from_data(records) # deterministic, from structured data
export <ontology> <path> [--format turtle]
engine.export_owl(onto, path, format="turtle")
engine.export_shacl(onto, path, format="turtle")
align <source_uri> <target_uri> <predicate>
engine.create_alignment(source_uri, target_uri, predicate)
engine.get_alignments(entity_uri)
engine.list_alignments()
evaluate <ontology>
Quality-gate an ontology (OntologyEvaluator / OntologyQualityReport under the hood).
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 Changed · +52 lines · +13 tokens per session b6dceddb39fa
- 1mo ago First seen · 38 lines · 20 tokens per session scan A b259570e4d09
ontology is a skill published in the GitHub repository semantica-agi/semantica (14,272 stars, last pushed today), licensed MIT. It adds 33 tokens to every session and 540 once invoked, about $0.0001 per session on Opus 5.5. 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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