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 synthesisengineering/synthesis-skills --skill synthesis-slack-syncgit clone --depth 1 https://github.com/synthesisengineering/synthesis-skillsWrote 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/synthesisengineering/synthesis-skills/synthesis-slack-sync)<a href="https://agentmods.dev/skills/synthesisengineering/synthesis-skills/synthesis-slack-sync"><img src="https://agentmods.dev/badge/skills/synthesisengineering/synthesis-skills/synthesis-slack-sync/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/synthesisengineering/synthesis-skills/synthesis-slack-sync"><img src="https://agentmods.dev/badge/skills/synthesisengineering/synthesis-skills/synthesis-slack-sync.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high System Prompt Leakage · line 121 Skill contains instructions that could directly expose system prompts, internal rules, or hidden instructions to users or external parties.Fix: Remove any instructions that reveal, print, or output system prompts or internal rules. System instructions should never be exposed to end users.
- medium Rogue Agent · line 23 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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 | $0.00085 | $0.06895 |
| Opus 5 | $0.00043 | $0.03447 |
| Sonnet 5 | $0.00017 | $0.01379 |
| Haiku 4.5 | $0.00009 | $0.00690 |
Grade A, and why
synthesis-slack-sync 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 6d 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 — 355 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Synthesis Slack Sync
A protocol for syncing Slack channels and threads to local transcript files using Slack MCP. Designed for AI-assisted workflows where an agent reads Slack on behalf of a user, saves transcripts locally, and updates a daily action plan.
This skill provides the protocol — the sync methodology, thread re-reading discipline, transcript format, and action plan update rules. A per-project config file provides the specifics: which channels, which paths, which DMs. Prefer .agents/slack-sync.yaml; existing .claude/slack-sync.yaml configs remain supported.
Version history and the incidents behind each rule: references/version-history.md. Transcript and permalink formats: references/transcript-formats.md. Draft templates: templates/draft-block.md and templates/sent-marker.md.
Configuration
Create .agents/slack-sync.yaml in each project that uses this skill. Existing .claude/slack-sync.yaml configs are valid compatibility fallbacks.
# .agents/slack-sync.yaml — Slack sync configuration (v3.1.0 schema)
#
# workspace: (REQUIRED) Workspace identifier. Used in transcript headers; must match
# the workspace-private repo name pattern ai-knowledge-<workspace>-<person>-private.
# slack_workspace_domain: (OPTIONAL but strongly recommended, v3.1.0+) The Slack
# workspace's URL host, e.g. "acme.slack.com". Used to construct clickable
# message permalinks in transcripts and draft messages. If absent, the skill
# falls back to the legacy bare-TS format and warns once per session.
# transcripts_repo: Absolute path to the workspace-private repo (Type 3). Transcripts
# are written at {transcripts_repo}/{transcripts_path}/{channels,dms,group-dms,meetings}/.
# transcripts_path: Relative subpath within transcripts_repo. Conventionally "transcripts".
# action_plan_repo: Absolute path to the person's personal ai-knowledge repo where daily
# action plans live. Daily plans are person-scoped (one per day, shared across all
# workspaces the person touches that day), so this does NOT point at the workspace-
# private repo.
# action_plan_path: Relative subpath within action_plan_repo. Conventionally "daily-plans".
# channels / dm_channels / group_dm_channels: as before.
workspace: example-workspace
slack_workspace_domain: example-workspace.slack.com
transcripts_repo: ~/workspaces/example-workspace/ai-knowledge-example-workspace-<person>-private
transcripts_path: transcripts
action_plan_repo: ~/workspaces/<person>/ai-knowledge-<person>
action_plan_path: daily-plans
channels:
- id: C0EXAMPLE01
name: team-general
type: public_channel
- id: C0EXAMPLE02
name: eng-pull-requests
type: private_channel
# Add more channels as needed
dm_channels: []
# - id: U0EXAMPLE01
# name: Jane Doe
# dm_id: D0EXAMPLE01
group_dm_channels: []
# - id: C0EXAMPLE03
# name: "Project Alpha team"
What ships with it
9 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.
- agents/openai.yaml 247 B
- references/transcript-formats.md 6.4 KB
- references/version-history.md 17 KB
- retrofit_permalinks.py 10 KB runs code
- scripts/preflight.py 7.2 KB runs code
- scripts/test_preflight.py 7.4 KB runs code
- templates/draft-block.md 5.6 KB
- templates/sent-marker.md 3.0 KB
- thread_checker.py 9.9 KB runs code
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.
- 6d ago Changed · -376 lines a0b008a12155
- 10d ago First seen · 731 lines · 85 tokens per session scan A 6d29add3b944
synthesis-slack-sync is a skill published in the GitHub repository synthesisengineering/synthesis-skills (18 stars, last pushed 3d ago), licensed Apache-2.0. It adds 85 tokens to every session and 6,895 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 2026-08-30.
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