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D3 · Foundation model limitations and how to mitigate them

Foundation model limitations and how to overcome them

No is perfect or "knows everything." Google Cloud expects a GenAI Leader to proactively identify the structural limitations of these models, know the recommended practices for mitigating them, and understand how a model is monitored in production on an ongoing basis.

Common limitations of foundation models

A foundation model is only as good (and as limited) as the data it was trained on and the way it is used. The exam expects you to recognize six structural limitations, with a concrete example of each.

1. Data dependency

The model's quality and behavior depend directly on the data used to train it. A model trained mainly on English-language text and Western content will perform worse when responding about cultural contexts, languages, or domains poorly represented in its training corpus.

2. Knowledge cutoff

The model only "knows" information up to its training cutoff date. If you ask it about an event, product, or price published after that date, the model won't know it — and it may make up a plausible-sounding answer instead of admitting it doesn't have that information (see hallucinations, below).

3. Bias

If the training data reflects historical or social biases present on the internet, the model can reproduce them. For example, a model may associate certain professions predominantly with one gender because that's how it appeared more frequently in the training texts, even though that association isn't correct or desirable.

4. Fairness

Related to bias, but focused on the unequal impact of the outcome: a credit-scoring or candidate-selection model can produce systematically less favorable results for certain demographic groups, even without being explicitly asked to consider those variables.

5. Hallucinations

A occurs when the model generates information that sounds convincing and coherent but is objectively false or is not backed by any real source — for example, citing an academic paper or a law that don't exist, with an appearance of total certainty.

6. Edge cases

Rare, ambiguous, or unusual inputs that the model didn't handle well during training. For example, a prompt with contradictory instructions, an atypical input format, or an unusual combination of languages within the same query can produce unpredictable results.

Recommended practices to mitigate these limitations

Google Cloud recommends five practices for proactively addressing these limitations. They aren't mutually exclusive — in practice they're combined — but it helps to think of them as a spectrum of increasing effort and investment.

PracticeWhat it solvesRelative effort
Anchors responses to verifiable data sources, reducing hallucinations and the impact of knowledge cutoffLow
Retrieves up-to-date, domain-specific information at query time, without retraining the modelLow-medium
Prompt engineeringGuides the model's behavior with clearer instructions, examples, and constraints, without changing the modelLow-medium
Adjusts the model's weights using your own data to specialize it for a specific domain, tone, or taskHigh
Adds human review and approval before a high-risk output is used or publishedHigh (operational, ongoing)

Watch out for this on the exam

None of these practices eliminates the limitations completely — they reduce them. Grounding and RAG are the first recommended levers because they don't require retraining the model. Fine-tuning and HITL are reserved for cases where prompt adjustment or context retrieval aren't enough, or where the risk of an error is high.

Continuous monitoring and evaluation of gen AI models

A gen AI model in production is not "set it and forget it." Google Cloud recommends a set of continuous monitoring practices because the model's behavior, input data, and business context change over time.

Automatic model updates

Providers release improved versions of models regularly; an update strategy (automatic or controlled) lets you benefit from quality and security improvements without staying tied indefinitely to an old version.

Key performance indicators (KPIs)

Business and quality metrics (accuracy, hallucination rate, user satisfaction, latency, cost per request) that let you objectively measure whether the model is still fulfilling its purpose.

Security patches and updates

Like any system in production, the models and the infrastructure that serves them require regular security patches to close known vulnerabilities.

Versioning

Recording and tracking exactly which model version (and which prompt or RAG pipeline version) was used to generate each response, so results can be reproduced and rolled back if a new version degrades quality.

Performance tracking

Continuous monitoring of latency, error rate, and response quality in production, compared against a baseline established before deployment.

Detects when the production input data (or the expected behavior) gradually drifts away from the data the model was originally evaluated on, which can degrade response quality over time without anyone noticing.

Agent Platform Feature Store

Agent Platform

A centralized repository for storing, serving, and reusing "features" (variables/attributes) consistently between training and production, within Google Cloud's agent ecosystem. Keeping features centralized and versioned makes it easier to detect drift and to ensure that agents use consistent, up-to-date data at every inference.

Did you get this topic?

Test what you just learned

A company deploys a gen AI assistant for customer support using Agent Platform. Six months later, they notice that response quality has silently declined, even though no change was made to the model. Which continuous monitoring practice is best suited to detect the root cause?

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