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 skills/zircote-plugins/adr/adr-format-y-statementnpx skills add zircote-plugins/adr --skill adr-format-y-statementgit clone --depth 1 https://github.com/zircote-plugins/adrWhat 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 | $0.00064 | $0.01072 |
| Opus 5 | $0.00032 | $0.00536 |
| Sonnet 5 | $0.00013 | $0.00214 |
| Haiku 4.5 | $0.00006 | $0.00107 |
Grade A, and why
adr-format-y-statement 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.
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.
Y-Statement ADR Format
The Y-Statement format, developed by Olaf Zimmermann, captures architectural decisions in a single structured sentence. It is the most concise ADR format available.
About Y-Statement Format
The Y-Statement format is:
- Concise - Core decision in one sentence
- Structured - Fixed format ensures completeness
- Traceable - Connects decision to context and consequences
- Quick - Minimal documentation overhead
The Y-Statement Structure
Basic Y-Statement
In the context of {use case/user story},
facing {concern/non-functional requirement},
we decided for {option}
and against {other options},
to achieve {quality/goal},
accepting {downside/consequence/trade-off}.
Extended Y-Statement
Adds a "because" clause for additional rationale:
In the context of {use case/user story},
facing {concern/non-functional requirement},
we decided for {option}
and against {other options},
to achieve {quality/goal},
accepting {downside/consequence/trade-off},
because {additional rationale}.
Template Structure
# {NUMBER}. {TITLE}
Date: {DATE}
## Status
{STATUS}
## Decision
In the context of {context},
facing {concern},
we decided for {chosen option}
and against {rejected options},
to achieve {quality goal},
accepting {trade-off}.
## Rationale
{Optional: Expand on the decision with additional context}
## Consequences
{Optional: List specific positive and negative outcomes}
Writing Y-Statements
Fill-in Guide
| Placeholder | What to Include | Example |
|---|---|---|
{context} |
Use case or scenario | "building a real-time notification system" |
{concern} |
Quality attribute or requirement | "the need for sub-second message delivery" |
{option} |
Chosen solution | "WebSockets" |
{other options} |
Alternatives rejected | "HTTP polling and Server-Sent Events" |
{quality} |
Goal achieved | "low-latency bidirectional communication" |
{trade-off} |
Accepted downside | "increased infrastructure complexity" |
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 3d ago First seen · 173 lines · 64 tokens per session scan A 0042eda03618
adr-format-y-statement is a skill published in the GitHub repository zircote-plugins/adr (5 stars, last pushed 16d ago), licensed MIT. It adds 64 tokens to every session and 1,072 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 2026-08-31.
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