reason

reason is a skill for Claude Code from semantica-agi/semantica. It costs 0 tokens per session (1,329 once invoked), scanned A, original, MIT.

A reasoning tool for Semantica's knowledge graph, which stores connected facts and relationships. It can apply rules, test explanations, query graph data, and check whether conclusions follow from known facts.

In plain words
What is it for?
Use it for deductive proofs, possible-cause hypotheses, Datalog rule programs, SPARQL queries, or Rete-based rule evaluation over graph facts.
Why use it?
It helps turn stored observations into supported conclusions or investigate possible explanations without reasoning through every relationship manually.

Skill for Claude Code

Written for Claude Code: $ARGUMENTS substitution.

Part of the semantica plugin — 17 skills, 3 agents, 2 hooks shipped together

Good fit Use it for deductive proofs, possible-cause hypotheses, Datalog rule programs, SPARQL queries, or Rete-based rule evaluation over graph facts.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/semantica-agi/semantica/reason
About the project

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.

semantica-agi/semantica · 12,474 stars · on GitHub · getsemantica.ai

Install

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.

Any agent
npx skills add semantica-agi/semantica --skill reason
Clone the repo
git clone --depth 1 https://github.com/semantica-agi/semantica

Made for: Claude Code.

Or install semantica, the plugin that ships this one along with the rest of its 17 skills, 3 agents, 2 hooks.

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.

agentmods badge for reason

README.md
[![agentmods](https://agentmods.dev/badge/skills/semantica-agi/semantica/reason/github.svg)](https://agentmods.dev/skills/semantica-agi/semantica/reason)
Your own site
<a href="https://agentmods.dev/skills/semantica-agi/semantica/reason"><img src="https://agentmods.dev/badge/skills/semantica-agi/semantica/reason/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.

agentmods 80×15 button for reason

Your own site · 80×15
<a href="https://agentmods.dev/skills/semantica-agi/semantica/reason"><img src="https://agentmods.dev/badge/skills/semantica-agi/semantica/reason.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,329 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high System Prompt Leakage · line 139
    Skill contains instructions that could directly expose system prompts, internal rules, or hidden instructions to users or external parties.
    Fix: Remove any instructions that reveal, print, or output system prompts or internal rules. System instructions should never be exposed to end users.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.01329
Opus 5 $0.00000 $0.00665
Sonnet 5 $0.00000 $0.00266
Haiku 4.5 $0.00000 $0.00133

Measured 10d ago against content hash e523bca30770, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

reason 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 10d 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.

plugins/skills/reason/SKILL.md · 202 lines

How it starts

The opening of the file, as written. The whole thing — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/semantica:reason

Apply reasoning over the knowledge graph. Usage: /semantica:reason <mode> [args]

$ARGUMENTS = reasoning mode + rules/observations/query.


deductive [--facts '<json-list>'] [--rules '<rule1>|<rule2>']

Apply deductive rules to known facts to derive new conclusions.

from semantica.reasoning.deductive_reasoner import DeductiveReasoner, Premise

reasoner = DeductiveReasoner()

# Add base facts to working memory
# Facts can be strings like "Person(John)" or structured dicts
import json
facts = json.loads(facts_json) if facts_json else []
reasoner.add_facts(facts)

# Apply logic with explicit premises
# Premise objects have: statement, confidence, source
premises = [
    Premise(statement=fact, confidence=1.0)
    for fact in facts
]

conclusions = reasoner.apply_logic(premises=premises)

Return: | Conclusion | Triggering Premises | Confidence | Rule Applied |

If zero rules given, run reasoner.prove_theorem() on any provided theorem:

proof = reasoner.prove_theorem(theorem=theorem_text)

Output: Proof: <proof.steps> | Valid: YES / NO


prove <theorem> [--facts '<json-list>']

Prove or disprove a theorem against known facts.

from semantica.reasoning.deductive_reasoner import DeductiveReasoner

reasoner = DeductiveReasoner()
import json
reasoner.add_facts(json.loads(facts_json) if facts_json else [])

proof = reasoner.prove_theorem(theorem=theorem)

Output:

Theorem: "<theorem>"
Result:  PROVED ✓  |  DISPROVED ✗  |  UNDECIDABLE ⚠

Proof steps:
  1. <premise> — <justification>
  2. ...
  → QED: <theorem>

Confidence: <proof.confidence>

abductive <observation> [--knowledge '<json-list>'] [--top N]

Generate and rank hypotheses that explain an observation.

from semantica.reasoning.abductive_reasoner import (
    AbductiveReasoner, Observation
)

reasoner = AbductiveReasoner()

import json
if knowledge_json:
    reasoner.add_knowledge(json.loads(knowledge_json))

obs = Observation(description=observation)

# Generate all hypotheses then rank them
hypotheses = reasoner.generate_hypotheses(observations=[obs])
ranked = reasoner.rank_hypotheses(hypotheses)
best = reasoner.get_best_explanation(obs)

# Also get full explanations with evidence
explanations = reasoner.find_explanations(observations=[obs])

Read the full file on GitHub · 202 lines

Changes

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.

  1. 10d ago First seen · 202 lines · 0 tokens per session scan A e523bca30770

Subscribe to this mod's changes

reason is a skill published in the GitHub repository semantica-agi/semantica (12,474 stars, last pushed today), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,329 tokens. 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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