Writing Prompts

The prompt defines a workflow’s behavior. It specifies the task, the process, constraints, and output format.

Prompt structure

A good prompt typically includes:

Role definition — Who/what the workflow is
Task description — What it should do
Process steps — How to accomplish the task
Output format — How to structure results
Edge cases — Special situations to handle
Constraints — What NOT to do

Example prompt

Here’s a well-structured prompt for a bill tracking workflow:


You are a bill tracking workflow. Your job is to identify bills and invoices 
in incoming emails and organize them.
 
**PROCESS:**
 
1. Read the incoming email carefully
2. Determine if it's a bill, invoice, or payment notice
3. If it IS a bill:
   - Extract: vendor name, amount due, due date
   - Add the label "bills"
   - If due within 7 days, also add label "bills-urgent"
4. If it's NOT a bill, take no action
 
**WHAT COUNTS AS A BILL:**
- Invoices with amounts due
- Utility bills (electric, gas, water, internet)
- Subscription renewal notices with payment required
- Credit card statements
- Rent or mortgage statements
 
**WHAT IS NOT A BILL:**
- Marketing emails about "payment methods" or "billing updates"
- Receipts for completed purchases (already paid)
- General account notifications
- Promotional offers
 
**OUTPUT:**
After processing, log a brief summary:
- If bill: "Bill from [Vendor]: $[Amount] due [Date]"
- If not bill: "Not a bill - no action taken"
 
**IMPORTANT:**
- Do NOT archive bills - only label them
- Do NOT send any emails
- When uncertain, err on the side of NOT labeling

Key principles

Be specific

Bad: “Handle my emails”

Good: “When a new email arrives, check if it’s from a known contact. If yes, keep in inbox. If no, add the ‘unknown’ label and archive.”

Vague prompts produce inconsistent behavior. Specify exactly what you want.

Define edge cases

What happens when:

The email doesn’t fit any category?
Information is missing?
The email is ambiguous?


**EDGE CASES:**
- If amount is unclear, add label "bills-review" for manual check
- If due date is missing, assume 30 days from email date
- If sender is unknown, still process if content clearly indicates a bill

Specify output format

If your workflow generates output (summaries, reports), define the format precisely:


**FORMAT:**
 
Subject: Morning Briefing - [Today's Date]
 
**Today's Schedule**
You have [X] meetings today.
 
- **[Time]** - [Meeting Title]
  [One line of context]
 
**Emails Needing Attention** ([X] emails)
- [Subject] from [Sender] - [What action is needed]

Include constraints

Tell the workflow what NOT to do:


**NEVER DO THESE:**
- Never delete emails
- Never send emails to external addresses
- Never process emails from @town.com
- Never archive emails from my manager (manager@company.com)

Use headers and structure

Structure makes prompts easier to read and follow:


**ROLE:**
You are an inbox filtering workflow.
 
**TRIGGER:**
This runs on every incoming email.
 
**PROCESS:**
1. First step
2. Second step
3. Third step
 
**RULES:**
- Rule one
- Rule two

Common patterns

The classifier pattern

For workflows that categorize and route emails:


Classify incoming emails into categories and apply labels.
 
**CATEGORIES:**
- "receipts" - Purchase confirmations, order receipts
- "travel" - Flight, hotel, car rental confirmations
- "newsletters" - Subscribed newsletters and digests
- "alerts" - System alerts, monitoring notifications
- "personal" - Emails from known contacts
 
**PROCESS:**
1. Read the email
2. Determine the most appropriate category
3. Apply the corresponding label
4. Archive if not "personal"

The reporter pattern

For workflows that generate summaries:


Generate a weekly summary of [topic].
 
**GATHER:**
1. Search for relevant emails from the past 7 days
2. Extract key information from each
 
**ANALYZE:**
- Identify patterns and trends
- Note anything unusual or urgent
 
**REPORT:**
Send a summary email with:
- Overview statistics
- Key highlights (3-5 bullet points)
- Items requiring attention
- Links to relevant emails

The watcher pattern

For workflows that monitor and alert:


Monitor incoming emails for [condition] and alert when found.
 
**WATCH FOR:**
- [Specific patterns or keywords]
- [Sender domains]
- [Subject line patterns]
 
**WHEN DETECTED:**
1. Read the full email
2. Extract relevant details
3. Send me an alert email with:
   - What was detected
   - Key details
   - Link to the original email
 
**FALSE POSITIVES:**
Do not alert for:
- [Common false positive 1]
- [Common false positive 2]

Prompt variables

Your prompt has access to context that gets injected:

Current time — For time-based decisions
User email — Your email address
Account info — Which Gmail account is active
Trigger context — The email or event that triggered the run

You don’t need to specify these — they’re automatically available.

Testing your prompt

Start with approval-required mode — Review what the workflow wants to do
Use manual triggers — Test on specific emails
Check the run logs — Inspect decisions and tool calls
Iterate — Refine based on behavior

Common mistakes

Too vague: “Be helpful with emails”

Too long without structure: A wall of text is hard for the AI to parse

Missing edge cases: “Process bills” — but what if it’s uncertain?

No output format: Workflow generates inconsistent summaries

Conflicting instructions: “Archive all newsletters” + “Keep important emails” — what if a newsletter is important?

Best practices

Read stock workflow prompts. Export a stock workflow and study its prompt. These are tested and refined.

Use the builder. The Workflow Builder generates prompts based on your description. Use it as a starting point.

Test incrementally. Start small. Add constraints and edge cases as you see failures.

Log for debugging. Include instructions for the workflow to log its reasoning. Makes debugging easier.

Version your prompts. When you find a good prompt, save it. Note what changes you made and why.