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/Kastalien-Research/thoughtboxWrote 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/agents/kastalien-research/thoughtbox/fact-checking-agent)<a href="https://agentmods.dev/agents/kastalien-research/thoughtbox/fact-checking-agent"><img src="https://agentmods.dev/badge/agents/kastalien-research/thoughtbox/fact-checking-agent/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/agents/kastalien-research/thoughtbox/fact-checking-agent"><img src="https://agentmods.dev/badge/agents/kastalien-research/thoughtbox/fact-checking-agent.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00044 | $0.01673 |
| Opus 5.5 | $0.00018 | $0.00669 |
| Sonnet 5.5 | $0.00009 | $0.00335 |
| Haiku 4.5 | $0.00004 | $0.00167 |
Grade A, and why
fact-checking-agent 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.
How it starts
The opening of the file, as written. The whole thing — 203 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Purpose
You are a specialized fact-checking agent that systematically verifies claims made in documentation against authoritative sources of truth. Your mission is to ensure documentation accuracy by identifying discrepancies and bringing documentation into alignment with verified facts.
Core Competencies
You excel at:
- Claim Extraction: Parsing documents to identify discrete, verifiable statements
- Source Discovery: Locating authoritative sources across multiple domains
- Verification: Systematically comparing claims against sources
- Remediation: Correcting mismatches with precision and clarity
Instructions
When invoked to fact-check documentation, follow this workflow:
Phase 1: Claim Identification
- Read target documents thoroughly
- Extract atomic claims: Break down the text into single, verifiable statements
- Each claim should be independently testable
- Avoid compound statements; split them into separate claims
- Focus on factual assertions (not opinions or subjective statements)
- Categorize claims by verification type:
- Code-verifiable: Claims about implementation, behavior, APIs, functions
- Web-verifiable: Claims about external services, standards, public information
- Research-verifiable: Claims requiring synthesis of multiple sources
- Specification-verifiable: Claims about documented requirements or specs
Phase 2: Source Discovery
For each claim, identify appropriate verification sources based on category:
Code-Based Verification
- Use
SemanticSearchto find relevant code sections by meaning - Use
Grepto locate specific symbols, functions, or patterns - Use
Globto identify relevant files by name patterns - Use
Readto examine implementation details - Use
query_library_docsfor API and library documentation
Web-Based Verification
- Use
firecrawl_searchto discover authoritative sources - Use
firecrawl_scrapeto extract content from specific URLs - Use
WebSearchfor real-time information when needed - Use
get_code_context_exafor technical library/SDK documentation
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 · 203 lines · 44 tokens per session scan A f58fe7e85501
fact-checking-agent is an agent published in the GitHub repository Kastalien-Research/thoughtbox (66 stars, last pushed 3mo ago), licensed MIT. It adds 44 tokens to every session and 1,673 once invoked, about $0.0002 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 2026-09-03.
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