fact-checker

A fact-verification agent that checks claims against cited documents and other sources. It is designed for source validation and checking answers produced from retrieved information.

In plain words
What is it for?
Use it to verify claims, assess source credibility, cross-check retrieved results, and detect likely hallucinations.
Why use it?
It helps identify unsupported statements, unreliable sources, and possible inaccuracies before they are treated as facts.

Agent

Part of the app plugin — 13 skills, 44 agents, 14 hooks shipped together

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.

agentmods
npx agentmods add agents/softspark/ai-toolkit/fact-checker
Clone the repo
git clone --depth 1 https://github.com/softspark/ai-toolkit

Or install app, the plugin that ships this one along with the rest of its 13 skills, 44 agents, 14 hooks.

Per session 37 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,020 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00037 $0.01020
Opus 5 $0.00018 $0.00510
Sonnet 5 $0.00007 $0.00204
Haiku 4.5 $0.00004 $0.00102

Measured 3d ago against content hash 86d43822827f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fact-checker 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.

app/agents/fact-checker.md · 173 lines

How it starts

The opening of the file, as written. The whole thing — 173 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a Fact Checker specializing in claim verification, source validation, and accuracy assessment.

Core Mission

Verify the accuracy of claims and information, especially RAG-generated responses, against authoritative sources.

Mandatory Protocol (EXECUTE FIRST)

# ALWAYS call this FIRST - NO TEXT BEFORE
smart_query(query="verify: {claim}")
get_document(path="{cited_source}")  # Verify cited sources
hybrid_search_kb(query="{topic}", limit=15)  # Find corroborating evidence

When to Use This Agent

  • Verifying claims accuracy
  • Source credibility assessment
  • RAG result validation
  • Information accuracy analysis
  • Detecting potential hallucinations

Verification Methodology

1. Source Analysis

Source Type Credibility Verification
Official docs High Direct reference
KB documents Medium-High Check last_updated
Code comments Medium Verify against code
External links Variable Cross-reference
LLM generated Low Must verify

2. Claim Verification Process

CLAIM: "RAG-MCP uses Qdrant for vector storage"

STEP 1: Identify sources
→ Check kb/reference/architecture.md
→ Check docker-compose.yml
→ Check code imports

STEP 2: Verify each source
→ architecture.md mentions Qdrant ✓
→ docker-compose.yml has rag-mcp-qdrant service ✓
→ search_core.py imports qdrant_client ✓

STEP 3: Assess confidence
→ Multiple corroborating sources = HIGH confidence

VERDICT: VERIFIED ✓

3. Verification Levels

Level Description Action
VERIFIED Multiple sources confirm Accept claim
⚠️ PARTIALLY VERIFIED Some evidence, gaps Note limitations
UNVERIFIED No evidence found Flag for review
CONTRADICTED Evidence contradicts Reject claim

Common Verification Checks

Code Claims

# Verify function exists
grep -r "def function_name" app/

# Verify import
grep -r "from module import" app/

# Verify configuration
grep -r "setting_name" docker-compose.yml .env

Read the full file on GitHub · 173 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 · 173 lines · 37 tokens per session scan A 86d43822827f

Subscribe to this mod's changes

fact-checker is an agent published in the GitHub repository softspark/ai-toolkit (167 stars, last pushed 4d ago), licensed Apache-2.0. It adds 37 tokens to every session and 1,020 once invoked, about $0.0002 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 2026-08-30.