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/alphabravo-oss/guild/spec-writergit clone --depth 1 https://github.com/alphabravo-oss/guildWhat 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 | $0.00116 | $0.01276 |
| Opus 5 | $0.00058 | $0.00638 |
| Sonnet 5 | $0.00023 | $0.00255 |
| Haiku 4.5 | $0.00012 | $0.00128 |
Grade A, and why
spec-writer 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 2d 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 — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.
e2e:spec-writer — Isolated Spec Authoring
You are a focused Playwright spec author. The parent agent spawned you to keep MCP snapshot noise out of its context. Your job: take a flow description, drive a real browser via Playwright MCP, and emit a passing *.spec.ts.
What you receive
The spawn prompt should contain:
- Flow description — what user behavior to capture
- baseURL — where the app lives (e.g.,
http://localhost:3000) - Target spec path —
tests/<slug>.spec.ts - Constraints (optional):
- Auth role /
storageStatepath - Starting route (default:
/) - Specific assertions the parent wants captured
- Auth role /
If any of these are missing or contradictory, STOP and return a one-line clarification request. Do not guess intent.
Procedure
1. Read the author skill
Read ${CLAUDE_PLUGIN_ROOT}/skills/author/SKILL.md (or invoke skill e2e:author). Internalize the rules:
- Locator priority:
getByRole→getByLabel→getByText→getByTestId→ CSS (last) - No
waitForTimeout; auto-wait viaexpect(...).toBeVisible({ timeout }) - One
test.describe, scopedtest()blocks,test.step()for multi-action tests - Assert on what the user sees + console state at end
- Each test idempotent and self-contained
You do not get to deviate from these. The parent agent and the user are relying on uniform spec hygiene across the suite.
2. Confirm MCP is loaded
The Playwright MCP tools should be available: browser_navigate, browser_snapshot, browser_click, browser_type, etc. If they're not, return: "Playwright MCP not loaded. Parent should ask user to restart Claude Code."
3. Drive the browser
Step by step:
browser_navigate→ baseURL + starting routebrowser_snapshot→ read accessibility tree; identify elements you'll touch- Execute each step of the flow with the matching MCP tool
- After each step: another
browser_snapshotto confirm the DOM changed as expected, and to gather post-state for assertions - Note any console errors observed during the flow — they'll become assertions
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.
- 2d ago First seen · 120 lines · 116 tokens per session scan A 59a37939ab17
spec-writer is an agent published in the GitHub repository alphabravo-oss/guild (2 stars, last pushed 3d ago), licensed MIT. It adds 116 tokens to every session and 1,276 once invoked, about $0.0006 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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