Building workflows Agent Skill

Build, edit, test, enable, and monitor PostHog workflows over MCP.

Context cost
15.7k tokensestimated from the bundle, loaded when it triggers
Bundle
3 files · 62.6 kBtext throughout, nothing executable
Licence
not declarednone named by its author
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Build, edit, test, enable, and monitor PostHog workflows over MCP. Author the action/edge graph so it runs and opens cleanly in the visual editor, then change drafts surgically with patch operations. Use when asked to build, set up, automate, change, fix, or debug a workflow, campaign, broadcast, drip sequence, or event-triggered automation in the workflows product.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

marketingmcp
Filed under

Sales & CRM

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md14.4 kB · preview
--- name: building-workflows ---
6# Building workflows
7
8A PostHog **workflow** is a directed graph: a list of **action nodes** (actions) wired by **edges** (edges), with exactly one trigger node that starts every run. You author that graph as JSON and ship it over MCP. Always call it a "workflow" to the user. "Hog flow" is the internal code name (HogFlow), not a user-facing term.
9
10The single biggest failure mode is **getting the graph JSON structurally wrong**. The backend stores actions/config as loose JSON, but the visual editor parses every node against a strict schema, so a malformed node saves but then **breaks the editor view** for the whole workflow. Before composing or editing any graph, read [references/graph-schema.md](references/graph-schema.md). It is the contract; do not improvise node shapes from these examples alone.
11
12## The lifecycle
13
14Work the workflow through these stages. Don't jump straight to enabling it.
15
161. **Compose the graph.** Build actions + edges per [references/graph-schema.md](references/graph-schema.md). For any function node, don't guess the template: list the live catalog with cdp-function-templates-list and read its required inputs with cdp-function-templates-retrieve.
172. **Create as a draft.** workflows-create. Every workflow is created draft; it does not execute yet.
183. **Test-run it.** workflows-test-run runs **one step at a time**. Start at the first step (omit current_action_id, or point it at the trigger) with sample globals ({event, person, groups}), shaped like the trigger's real payload: an event trigger needs an event matching its filters, and an internal-event trigger needs an event named in its filters.events (for the Slack trigger, a $slack_message_received event with the Slack property bag) and no person (see [references/graph-schema.md](references/graph-schema.md)). A status=skipped result means this payload would not fire the trigger: if you fabricated the payload, fix it to match the trigger; if it came from a real past run (workflows-get-invocation), the trigger's filter is wrong, not the payload. The result includes the next step's id (nextActionId). Feed that back as current_action_id and run again, walking step by step to the end. Skip delay nodes by jumping to the action after them (delays aren't simulated). Async side effects (HTTP/email/SMS/push) are mocked unless you set mock_async_functions=false. Read each step's trace to confirm the path taken.
194. **Read logs while iterating.** workflows-logs shows the per-step execution trace (levels DEBUG to ERROR). This is how you see _why_ a step skipped, branched, or errored.
205. **Edit, then re-test.** Patch the graph with workflows-patch-graph (see [Editing a draft](#editing-a-draft)). **Every edit invalidates your earlier test** — re-run the affected path before moving on. On a draft workflow, edits apply directly; on an active one they stage a draft (see [Changing a live workflow](#changing-a-live-workflow)).
216. **Enable (needs the user's explicit sign-off).** workflows-enable flips it to active and an **event/webhook/manual** trigger starts firing on matching activity. From then on it runs on real people, and every change goes through the draft → test → publish cycle before taking effect — so finish testing, then get the user's explicit go before enabling. Don't enable on your own initiative.
227. **Dispatch (batch/schedule only).** A batch or schedule workflow does **not** fire on enable alone. Send a one-off broadcast with workflows-run-batch, or attach a recurring schedule with workflows-schedule-create. A batch trigger fans out to a person audience, so scheduling it needs the workflows-blast-radius preview and its confirm token; a schedule trigger runs once per occurrence with no audience, so schedule it directly. Confirm with workflows-get that status=='active' _and_ its read-only schedules field has an active entry.
238. **Monitor.** Drill down: workflows-global-stats (which workflows are failing) to workflows-stats (one workflow's trend) to workflows-list-invocations (who it failed for) to workflows-get-invocation (the triggering payload) to workflows-logs (the failing step).
24
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md2,008 words
Files3
Licencenot declared
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈100
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
15,550
on trigger
The instruction body and 2 supporting files, read only when the skill fires.
7.8%
of a 200k window
Ten skills this size would take about 78% of the window before you open a file.
050k100k150k200k context window

15.7k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

3 files, 62.6 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md14.4 kB
  • references/graph-schema.md41.5 kB
  • references/lifecycle-and-debugging.md6.7 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 3 files you can review in full before installing.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Building workflows · 15.7k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/building-workflows/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/building-workflows" ] && { [ ! -e .claude/skills/building-workflows ] || { mv .claude/skills/building-workflows "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/building-workflows" .claude/skills/ && echo "Installed .claude/skills/building-workflows"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add posthog/building-workflows

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/building-workflows/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/building-workflows/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/building-workflows" ] && { [ ! -e ~/.claude/skills/building-workflows ] || { mv ~/.claude/skills/building-workflows "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/building-workflows" ~/.claude/skills/ && echo "Installed ~/.claude/skills/building-workflows" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/building-workflows/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referenceposthog/building-workflows

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

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