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/giannimassi/webview-cli/skillnpx skills add giannimassi/webview-cli --skill skillgit clone --depth 1 https://github.com/giannimassi/webview-cliWhat 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 | $0.00135 | $0.04368 |
| Opus 5 | $0.00068 | $0.02184 |
| Sonnet 5 | $0.00027 | $0.00874 |
| Haiku 4.5 | $0.00014 | $0.00437 |
Grade A, and why
webview 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.
How it starts
The opening of the file, as written. The whole thing — 268 lines — stays where its author put it; the contents beside it link to each section on GitHub.
webview — Native macOS Agent UI
Open a native webview window from an agent workflow, let the user interact, get structured JSON back. Replaces terminal Q&A with a proper UI when it helps.
Execution contract [NON-NEGOTIABLE]
You — the agent — always run webview-cli via the Bash tool. Never ask the user to paste a command. The binary blocks until the user interacts with the window, then prints JSON to stdout. Your Bash call returns when the user clicks a button (or cancels/times out). Parse the result and proceed.
If running the command feels risky, ask for permission to run it — not to paste it. In auto mode, just run it.
When to use
| Situation | Use this skill? |
|---|---|
| Agent needs approval with context (diff, summary, risk) before a destructive action | Yes — richer than [y/N] |
| Collecting 3+ related fields (name + role + options) | Yes — one form beats N questions |
| Presenting 5-20 options to choose from | Yes — radio/select picker |
| Showing a diff/preview/report before user confirms | Yes — formatted content is readable |
| Reviewing a markdown doc (spec, PR description, draft) with comments/edits | Yes — use --markdown mode (Mode 3) |
| Letting the user browse/edit files in a directory (tree, syntax highlighting, md preview) | Yes — use --editor <path> mode (Mode 5) |
| Simple yes/no question | No — just ask in terminal |
| Agent-side computation taking >30s before UI can render | No — show a text status instead |
| Non-interactive environment (CI, piped output) | No — preflight will fail, fall back to terminal |
Preflight (run EVERY invocation)
# Binary on PATH?
if ! command -v webview-cli >/dev/null 2>&1; then
echo "ERROR: webview-cli not installed. Run: brew tap giannimassi/tap && brew install webview-cli" >&2
exit 1
fi
# macOS-only?
if [ "$(uname -s)" != "Darwin" ]; then
echo "ERROR: webview-cli requires macOS (detected $(uname -s))." >&2
exit 1
fi
What ships with it
3 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.
- yesterday First seen · 268 lines · 135 tokens per session scan A d6d0b7107db3
webview is a skill published in the GitHub repository giannimassi/webview-cli (11 stars, last pushed 2mo ago), licensed MIT. It adds 135 tokens to every session and 4,368 once invoked, about $0.0007 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.
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