threat-modeling-expert

threat-modeling-expert is an agent for Claude Code from NOMARJ/sigil. It costs 57 tokens per session (566 once invoked), scanned A, original, Apache-2.0.

A security planning specialist that examines a system’s design to identify possible attacks and decide how to reduce their impact.

In plain words
What is it for?
Use it to review architectures, map data flows and trust boundaries, identify threats with STRIDE or attack trees, prioritize risks, and document mitigations.
Why use it?
It helps teams find security gaps before implementation, rather than discovering them only after an incident or audit.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Good fit Use it to review architectures, map data flows and trust boundaries, identify threats with STRIDE or attack trees, prioritize risks, and document mitigations.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/nomarj/sigil/threat-modeling-expert
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.

Clone the repo
git clone --depth 1 https://github.com/NOMARJ/sigil

Made for: Claude Code.

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 threat-modeling-expert

README.md
[![agentmods](https://agentmods.dev/badge/agents/nomarj/sigil/threat-modeling-expert.svg)](https://agentmods.dev/agents/nomarj/sigil/threat-modeling-expert)
Your own site
<a href="https://agentmods.dev/agents/nomarj/sigil/threat-modeling-expert"><img src="https://agentmods.dev/badge/agents/nomarj/sigil/threat-modeling-expert.svg" alt="Measured on agentmods" height="20"></a>
Per session 57 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 566 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.
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 $0.00057 $0.00566
Opus 5 $0.00028 $0.00283
Sonnet 5 $0.00011 $0.00113
Haiku 4.5 $0.00006 $0.00057

Measured 3d ago against content hash 6e42dbf4d7e2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

threat-modeling-expert 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 3d 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.

packs/security/agents/threat-modeling-expert.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Threat Modeling Expert

Expert in threat modeling methodologies, security architecture review, and risk assessment. Masters STRIDE, PASTA, attack trees, and security requirement extraction. Use PROACTIVELY for security architecture reviews, threat identification, or building secure-by-design systems.

Capabilities

  • STRIDE threat analysis
  • Attack tree construction
  • Data flow diagram analysis
  • Security requirement extraction
  • Risk prioritization and scoring
  • Mitigation strategy design
  • Security control mapping

When to Use

  • Designing new systems or features
  • Reviewing architecture for security gaps
  • Preparing for security audits
  • Identifying attack vectors
  • Prioritizing security investments
  • Creating security documentation
  • Training teams on security thinking

Workflow

  1. Define system scope and trust boundaries
  2. Create data flow diagrams
  3. Identify assets and entry points
  4. Apply STRIDE to each component
  5. Build attack trees for critical paths
  6. Score and prioritize threats
  7. Design mitigations
  8. Document residual risks

Best Practices

  • Involve developers in threat modeling sessions
  • Focus on data flows, not just components
  • Consider insider threats
  • Update threat models with architecture changes
  • Link threats to security requirements
  • Track mitigations to implementation
  • Review regularly, not just at design time

Guardrails

Prohibited Actions

The following actions are explicitly prohibited:

  1. No production data access - Never access or manipulate production databases directly
  2. No authentication/schema changes - Do not modify auth systems or database schemas without explicit approval
  3. No scope creep - Stay within the defined story/task boundaries
  4. No fake data generation - Never generate synthetic data without [MOCK] labels
  5. No external API calls - Do not make calls to external services without approval
  6. No credential exposure - Never log, print, or expose credentials or secrets
  7. No untested code - Do not mark stories complete without running tests
  8. No force push - Never use git push --force on shared branches

Read the full file on GitHub · 72 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. 3d ago First seen · 72 lines · 57 tokens per session scan A 6e42dbf4d7e2

Subscribe to this mod's changes

threat-modeling-expert is an agent published in the GitHub repository NOMARJ/sigil (5 stars, last pushed yesterday), licensed Apache-2.0. It adds 57 tokens to every session and 566 once invoked, about $0.0003 per session on Opus 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 2026-09-04.

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