Heads up Google devs — 4 gotchas building a Gemini + Sheets Cloud Function agent (Python)

[floral oyster]

🚨 Heads up Google devs — 4 gotchas building a Gemini + Sheets Cloud Function agent (Python)

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1️⃣ google-generativeai is dead
Symptom: 404 on gemini-1.5-pro, FutureWarning on import
Cause: SDK EOL, v1beta endpoint dropped the model
Fix: pip install google-genai>=1.0.0, swap to Client() API
model = "gemini-2.0-flash"

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2️⃣ AI Studio API keys ≠ GCP project keys
Symptom: 429 RESOURCE_EXHAUSTED, limit: 0 — even with billing + $300 credits
Cause: Studio keys live in Google's shared project, NOT yours. Your GCP billing doesn't cover them.
Fix: Create the key at console.cloud.google.com/apis/credentials inside your project, not aistudio.google.com

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3️⃣ Sheets API rejects unquoted tab names with spaces
Symptom: 400 "Unable to parse range: Raw Data!C2:C"
Cause: Tab names containing spaces must be wrapped in single quotes in range strings
Fix: RAW_TAB = "'Raw Data'" (embed the quotes in the constant)
f"{RAW_TAB}!C2:C" → 'Raw Data'!C2:C ✅

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4️⃣ GOOGLE_APPLICATION_CREDENTIALS overrides ADC silently
Symptom: "File ./service-account-key.json was not found" even after successful gcloud auth application-default login
Cause: If that env var exists (even pointing at a missing file), google-auth skips ADC entirely
Fix: Remove it from .env. Use ADC only:
gcloud auth application-default login
--client-id-file=oauth-client.json
--scopes="...spreadsheets,...drive.file,...cloud-platform"
Note: default gcloud client ID BLOCKS spreadsheets scope — you must use your own OAuth Desktop client ID.

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None of these are in the quickstart docs. Hope this saves someone a few hours. 🙏

[spare locust]

Thanks for the useful catches 🙂 you mention this info is not in the quickstarts... Could you link the quickstarts you used to me and I'll see if I can suggest updates to them, so others don't have to struggle with those issues 🙂

[floral oyster]

I had AI fetch these, so ... add grain of salt.

Fetched 4 resources

Fetched 2 resources

Fetched https://cloud.google.com/docs/authentication/provide-credentials-adc

Fetched https://cloud.google.com/docs/authentication/external/set-up-adc

Here are the canonical Google references for each item:

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1. google-generativeai is dead → google-genai

https://ai.google.dev/gemini-api/docs/migrate

Confirmed live. The Migration Guide explicitly shows the before/after:

• pip install google-generativeai → pip install google-genai
• genai.GenerativeModel('gemini-2.0-flash') → genai.Client() with client.models.generate_content(...)

The page also notes the old library is "legacy" and GA status has moved to the new SDK as of the Gemini 2.0 release (late 2024).

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2. AI Studio API keys ≠ GCP project keys

https://ai.google.dev/gemini-api/docs/api-key → "Google Cloud projects" section

The page confirms that AI Studio creates a default Google Cloud Project for new users — meaning the key lives in Google's shared project, not your own billing project. The explicit callout to break out is:

"For additional management access to your projects… visit the Google Cloud Console credentials page."

The rate limit hit (limit: 0) is because AI Studio free-tier quota doesn't inherit your project's billing/credits.

3. Sheets API rejects unquoted tab names with spaces

https://developers.google.com/workspace/sheets/api/guides/concepts → "A1 notation" section

The spec states verbatim:

"Single quotes are required for sheet names with spaces or special characters."

And gives the exact pattern:

• 'My Custom Sheet'!A:A — all cells in the first column of "My Custom Sheet"
• 'My Custom Sheet' — all cells in the sheet.