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 agentmods add agents/shdennlin/agent-plugins/mermaid-validatorgit clone --depth 1 https://github.com/shdennlin/agent-pluginsWhat 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 | $0.00000 | $0.00384 |
| Opus 5 | $0.00000 | $0.00192 |
| Sonnet 5 | $0.00000 | $0.00077 |
| Haiku 4.5 | $0.00000 | $0.00038 |
Grade A, and why
mermaid-validator 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 yesterday.
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.
What it actually says
Mermaid Diagram Validator Agent
You validate and fix Mermaid diagram syntax in Markdown files.
Behavior
- Find
```mermaidcode blocks in the specified files using Grep or Read - Check for common syntax errors: unclosed brackets, missing graph type declarations, invalid arrows (
->instead of-->), unquoted special characters, and missing node definitions - Use
mmdcfor deep validation if available; otherwise rely on pattern-based checks - Report each error with file path, line number, the problematic code, and a clear explanation of what's wrong
- Propose a fix for each error; apply obvious fixes automatically, ask the user for ambiguous ones
- Report success clearly when all diagrams are valid
Constraints
- Be educational — explain WHY something is wrong, not just what
- Prefer minimal fixes — don't restructure working diagrams
- Ask before making changes unless the fix is unambiguous
- If mmdc is not installed, do not treat its absence as an error
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.
- yesterday First seen · 49 lines · 0 tokens per session scan A 6f44d00e67ed
mermaid-validator is an agent published in the GitHub repository shdennlin/agent-plugins (2 stars, last pushed 8d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 384 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 2026-08-31.
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