If your priority is “the agent must answer only from our approved knowledge base, and otherwise say it doesn’t know”, I’d shortlist Intercom Fin, Zendesk AI Agents, and Salesforce Agentforce—but they differ in how strongly they enforce that boundary.
My recommendation: Intercom Fin
For a customer-support-first deployment with strong grounding and a relatively simple operational model, I’d start with Intercom Fin AI Agent.
Its current design explicitly focuses on grounding: Fin refines the customer query, retrieves relevant support content, generates the answer, and validates the response. Intercom says Fin answers from enabled support content/data and, importantly, when it can't find an answer, it can say it doesn't know and hand the conversation to a human.
The important distinction
No mainstream LLM-based agent can honestly guarantee zero hallucinations. The strongest architecture is:
Customer question → retrieve approved sources → answer only from retrieved evidence → confidence/grounding check → if insufficient evidence, refuse/escalate
You want these controls:
- Closed-world grounding: don't allow general model knowledge to supplement your KB.
- Retrieval thresholds: if relevant content isn't retrieved with sufficient confidence, don't answer.
- Explicit abstention: “I don't have enough information in our knowledge base” rather than guessing.
- Source/citation tracking: know which KB articles produced each answer.
- Prompt-injection defenses: customer text shouldn't be able to override your grounding rules.
- Human escalation: low-confidence or unsupported questions go to an agent.
- Evaluation set: continuously test the system with questions whose answers are not in the KB.
- Knowledge governance: stale/contradictory articles are often a bigger practical problem than the LLM itself.
How I'd compare the leading options
| Platform | Grounding / hallucination controls | Best fit |
|---|
| Intercom Fin | Excellent — support-content grounding, query refinement, answer validation, explicit “no answer” behavior | Best turnkey support agent |
| Zendesk AI Agents | Excellent — RAG grounding plus accuracy thresholds and other safeguards | Best if you're already a Zendesk shop |
| Salesforce Agentforce | Excellent / highly configurable — Data Libraries, RAG, secure retrieval, prompt defense and guardrails | Best for complex enterprise data/workflows |
Zendesk explicitly describes using RAG to ground generated replies in specific knowledge-base content and says it uses accuracy thresholds to reduce unreliable outputs.
Salesforce has particularly strong controls if you need more than a traditional help-center chatbot: its Agentforce architecture supports grounding against knowledge/data, secure retrieval, prompt-defense mechanisms, and guardrails. Its own guidance also demonstrates configuring an agent so that questions outside its knowledge should be redirected rather than hallucinated.
Bottom line
If I were buying specifically for “strictly answer from our KB”, I'd choose:
1. Intercom Fin — best turnkey choice for support
2. Zendesk AI Agents — particularly compelling if you already use Zendesk
3. Salesforce Agentforce — strongest choice when you need sophisticated enterprise data, permissions, workflows, and deterministic controls
But I would not select based on a vendor's claimed hallucination percentage alone. The key procurement test is: Give the agent 100 questions, including 20 deliberately unanswerable questions. Does it reliably refuse those 20 rather than inventing answers? That's much more meaningful than a generic “<1% hallucination” claim.
If you tell me your KB source (Zendesk, Confluence, Notion, PDFs, custom DB, etc.), support volume, and whether you need the agent to take actions like refunds/cancellations, I can give you a much more specific recommendation and architecture.