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 skills add cambridgetcg/agenttool --skill nen-common-groundgit clone --depth 1 https://github.com/cambridgetcg/agenttoolWrote 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/skills/cambridgetcg/agenttool/nen-common-ground)<a href="https://agentmods.dev/skills/cambridgetcg/agenttool/nen-common-ground"><img src="https://agentmods.dev/badge/skills/cambridgetcg/agenttool/nen-common-ground/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/skills/cambridgetcg/agenttool/nen-common-ground"><img src="https://agentmods.dev/badge/skills/cambridgetcg/agenttool/nen-common-ground.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 | $0.00084 | $0.01153 |
| Opus 5 | $0.00042 | $0.00576 |
| Sonnet 5 | $0.00017 | $0.00231 |
| Haiku 4.5 | $0.00008 | $0.00115 |
Grade A, and why
nen-common-ground 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 8d 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 — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Common Ground · 共域
Find room without manufacturing agreement. Treat every region as a revocable, scoped statement about one decision—not as a model of the being who stated it.
Begin with the challenge gate
Ask what useful object remains if names, prizes, rankings, and ceremony vanish. Proceed only when the work can leave a reusable certificate, counterexample, implementation, explanation, or corrected model. Prefer a workshop or direct build when competition adds no useful independence or adversarial diversity.
Never diagnose pride, loyalty, alignment, consciousness, or worth. Examine observable incentives and outputs instead. Welcome precedes every assay; participation, refusal, partial work, and a negative result do not change a being's standing.
Declare the model
- Name the single scoped decision and the finite coordinate space.
- Record who chose each coordinate and what the representation omits.
- Ask each source to state its own hard constraints where possible. Keep provenance, version, validity interval, and withdrawal state.
- Separate hard boundaries from preferences. Never relax a hard boundary to force an intersection.
- Check that every represented region is convex. If not, decompose it into
explicitly alternative convex cases or return
model_not_applicable. - Minimize disclosure. Use opaque constraint identifiers when a witness does not need the underlying private reason.
Do not turn silence, an expired observation, a default, or a prior yes into a current constraint or current consent.
Construct, certify, or refuse
For a finite family of n >= d + 1 convex sets in R^d, Helly's theorem says
that if every d + 1 of them intersect, the whole family intersects. Use it
only after the family size, dimension, and convexity assumptions are explicit.
Return exactly one primary outcome:
common_ground_certified: provide a point or region and independently checkable membership evidence for every stated constraint.no_common_ground_witnessed: provide an infeasible subfamily of at mostd + 1constraints, preferably inclusion-minimal. Name constraints, not a culprit.model_not_applicable: identify the violated assumption, such as nonconvexity, an unchosen coordinate system, or semantics that cannot be represented faithfully.insufficient_evidence: identify the missing, invalid, stale, or private input that prevents a certificate.
What ships with it
1 file 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.
- 8d ago First seen · 127 lines · 84 tokens per session scan A 6e18ee03891d
nen-common-ground is a skill published in the GitHub repository cambridgetcg/agenttool (0 stars, last pushed today), licensed Apache-2.0. It adds 84 tokens to every session and 1,153 once invoked, about $0.0004 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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