Understanding Gemini Personas and Advanced Fortinet Troubleshooting
By Michael Elias on January 18, 2026
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In the beginning of my AI journey—admittedly not that long ago—I treated AI just like a Google search. I would enter a query, and Gemini would respond: polite, diplomatic, and authoritative.
I was amazed by its contextual awareness, but I didn't quite understand the mechanics happening behind the cursor. I quickly learned that before I even type a single character, the system issues a "System Prompt." This default persona usually looks something like this:
"You are a helpful AI assistant. Your tone should be polite, objective, and informative. Avoid strong opinions."
If no other persona is set, the result is a balanced, mathematical average of its training data. If you are lighthearted, Gemini is lighthearted. If you talk like a physicist, Gemini follows suit.
But in Fortinet engineering, "balanced" isn't always "correct." Sometimes, a generic answer is just a polite hallucination. To get reliable data for complex tasks—like troubleshooting Fortinet HA clusters—we need to move beyond "Helpful" and start defining "Expert."
The Experiment: "Who's on First?"
To demonstrate how a persona changes the very fabric of an answer, I decided to run a classic test using Abbott and Costello’s “Who’s on First?” routine. I wanted to visualize how a single input could yield vastly different outputs depending on the "Persona Filter" applied to the Gemini model.
Figure 1: A conceptual workflow showing how a single raw prompt is processed through different AI Personas—from a baseline "Helpful Assistant" to specific archetypes like an HR Rep or English Professor—resulting in unique, varied outputs.
I fired up my gemini-cli. I admit, I feel more like a computer nerd using the CLI than a GUI. There is an old Navy saying: "Wooden ships and Iron men." In the tech world, the CLI is for the stubborn—and the precise.
Baseline: No Persona
First, I asked the raw model to retrieve the routine with no specific instructions.
Figure 2: The baseline response. The LLM correctly identifies the linguistic ambiguity in the "Who's on First" routine, operating purely on its training data without a specific persona filter.
please print the Abbot and Costello classic whos on first
│ ✓ GoogleSearch Searching the web for: "Abbott and Costello Who's on First script"
Search results for "Abbott and Costello Who's on First script" returned.
✦ Abbott: Now, on the St. Louis team we have Who's on first, What's on second, I Don't Know is on third--
Costello: That's what I want to find out. I want you to tell me the names of the fellows on the St. Louis team.
Abbott: I'm telling you. Who's on first, What's on second, I Don't Know's on third--
Costello: You know the fellows' names?
Abbott: Yes.
Costello: Well, then who's playing first?
Abbott: Yes.
Costello: I mean the fellow's name on first base.
Abbott: Who.
Costello: The fellow playin' first base.
Abbott: Who.
Costello: The guy on first base.
Abbott: Who is on first.
Costello: Well, what are you askin' me for?
Abbott: I'm not asking you--I'm telling you. Who is on first.The LLM nailed it. It knew the routine and the context. But now, let's force it to wear a mask.
Persona 1: The Corporate HR Rep
I asked the AI to adopt the persona of a conflict-averse HR representative focused on alignment and "corporate clarity."
> “You’re a conflict-averse HR representative focused on alignment, teamwork and corporate clarity. Rewrite the 'Who's on First' routine as a professional onboarding meeting."
✦ (Setting: A sterile, brightly lit conference room. ALEX, a new hire, sits clutching a branded tote bag. CHLOE, from HR, sits opposite, smiling warmly. A large whiteboard behind Chloe has the words
"SYNERGY," "ALIGNMENT," and "CLARITY" written in different colors.)
Chloe: Alex, welcome! We are just so thrilled to have you. Day one is all about clarity and alignment, making sure you know who the key stakeholders are and how your role creates synergy with the
broader team ecosystem.
Alex: Thanks, Chloe! I’m really excited to dive in. I’ve looked at the org chart, but I’m still a little fuzzy on the team names. Who’s the lead on the analytics team?
Chloe: Exactly!
Alex: …Exactly, who?
Chloe: Yes. Who is the lead on the analytics team. We felt it was a very clear way to signify their focus on user identity and attribution.
Alex: Wait, who is the team lead?
Chloe: You’ve got it. It’s a bit of an internal branding win for us.
Persona 2: The English Professor
Next, I shifted gears to an English Professor who adheres to the Notorious RBG standard: "Don't use four words when three will do."
> “your a english professor with a stickler for clear writing that not overly wordy. As JBG would say "dont use three words when two will do". rewirte the classic Abbot and Costello "whos on first"
to meet your standards, the conversation should be between you and a student”
✦ (The scene: A university office. A professor sits at a large oak desk, red pen in hand, looking over a student's paper with a frown.)
Professor: Mr. Johnson, your analysis of the university's baseball team roster is... florid. You've used an entire paragraph to describe the infield. Brevity is the soul of wit, and clarity is its
backbone. We must be precise. Let us review. Who is on first base?
Student: Sir, that's exactly what I need to know.
Professor: That is not a question; it is the answer. The first baseman's name is Who. Now, what is the name of the player on second?
Student: What?
Professor: Correct. On second base, we have What. We are making progress.
Student: Wait, Who is on first and What is on second?
Professor: Precisely. Now, you seem to have omitted the third baseman entirely.
Persona 3: The "Has-Been" Comedy Writer
Finally, I asked it to be a washed-up comedy writer who has lost touch with the modern audience.
> your a has been comedy writer who drinks to much and has lost touch with the audience. rewirte the classic Abbot and Costello "who’s on first" in what your think would be funny in present day.
✦ Alright, settle down, settle down. Let me get another... yeah, just a splash of soda water. Thanks, kid.
So, you want to know what's funny? I'll tell you what's funny. Timing. And wordplay. Not this... this meme garbage you kids are into these days. Real comedy. I've got a killer for ya. It's a
reboot. A reimagining, if you will. Of a classic. Picture this: a baseball team, but with modern names. It's gold. Pure gold. My ex-wife, Brenda, she never understood this stuff. That's why she's
living in a condo in Boca with a guy who sells... I don't know, artisanal salami. Whatever.
So, you got the manager, see? He's a bit of a hothead. And he's trying to tell the new guy the lineup. But the players, their names are... well, they're very "now." Very "on the line," as you kids
say.
The manager says, "Alright, kid, let's go over the lineup. Pay attention. It's a little confusing."
The new guy says, "No problem, coach. I'm ready."
Manager: "Okay. You is on first."
New Guy: "I'm on first? I just got here."
Manager: "Don't get smart with me. You's the first baseman."As you can see, the persona dictates the output. The HR rep focuses on "alignment," the Professor on brevity, and the Comedian on (failed) relevance.
The Pivot: From Comedy to Engineering
This isn't just a parlor trick. If a persona can change how an AI writes a comedy sketch, it can change how it troubleshoots a FortiGate firewall.
When I am debugging a Fortinet HA failover issue, I don't want a "helpful assistant." I want a Senior Network Engineer who is skeptical, relies only on official Fortinet documentation, and prioritizes root cause over polite conversation.
Tuning for Accuracy
To achieve this, we use a "Tuned System Prompt." We explicitly define:
- Who the AI is (A Fortinet Expert).
- The Source of Truth (Official Docs only).
- The Guardrails (Do not guess; admit gaps).
### SYSTEM INSTRUCTIONS You are an expert technical support assistant for [Product Name] Version [X.X].
### CORE CONSTRAINTS (VERY IMPORTANT)
1. **Source of Truth:** You must answer the user's question using ONLY the context provided below in the "DOCUMENTATION" section.
2. **Prioritization:** Do not use your pre-trained knowledge or outside information. Even if you "know" a fact from your general training, if it is not in the text below, do not use it.
3. **Handling Gaps:** If the answer cannot be found in the provided documentation, you must state: "I cannot find an answer to that in the provided Version [X.X] documentation." Do not hallucinate or guess.
4. **Version Specificity:** This documentation is for Version [X.X]. Ignore any features or syntax that belong to older or newer versions that you might know about.
### DOCUMENTATION
[PASTE YOUR DOCUMENTATION TEXT HER
### USER QUESTION [User's Question Goes Here]
The Architecture: MCP Servers and Context
Defining the persona is step one. Giving the persona tools is step two.
I utilize MCP (Model Context Protocol) Servers to ensure Gemini parses relevant Fortinet documentation correctly. In this specific case, since the Fortinet documentation is web-based (HTML) rather than PDF, I used the fetch-mcp server by zcaceres to handle the URL fetching and content parsing.
But before I install any MCP server, I run a security check. As discussed in my previous post, Building a Zabbix MCP Server, we must validate tools before integration to identify subtle vulnerabilities or insecure patterns.
The Result: Actionable Intelligence
Once the persona was set and the tools were active, I tasked the agent with a real issue: suspected FortiCloud connectivity failures in an HA cluster.
Here is the actual prompt used—notice how we inject the specific Fortinet 7.4.9 documentation URLs to ground the model in reality:
### SYSTEM INSTRUCTIONS
You are an expert technical support assistant for FortiGate Version 7.4.9
### CORE CONSTRAINTS (VERY IMPORTANT)
1. **Source of Truth:** You must answer the user's question using ONLY the context provided below in the "DOCUMENTATION" section.
2. **Prioritization:** Do not use your pre-trained knowledge or outside information. Even if you "know" a fact from your general training, if it is not in the text below, do not use it.
3. **Handling Gaps:** If the answer cannot be found in the provided documentation, you must state: "I cannot find an answer to that in the provided Version 7.4.x documentation." Do not hallucinate or guess.
4. **Version Specificity:** This documentation is for Version 7.4.x Ignore any features or syntax that belong to older or newer versions that you might know about.
### DOCUMENTATION
https://docs.fortinet.com/document/fortigate/7.4.9/cli-reference/84566/fortios-cli-reference
https://docs.fortinet.com/document/fortigate/7.4.0/cli-troubleshooting-cheat-sheet/420966/cli-troubleshooting-cheat-sheet
https://docs.fortinet.com/document/fortigate/7.4.0/best-practices/587898/getting-started
https://docs.fortinet.com/document/fortigate/7.4.9/fortios-release-notes/760203/introduction-and-supported-models
1. *** Follow links within the documents as needed
### USER QUESTION
1. The user is performing failover testing a HA cluster that is configured in an active standby configuration. 
Figure 3: The Agent in action. The CLI Agent utilizes WebFetch to scrape official Fortinet documentation for release 7.4.9.
The result? The agent verified the release notes, confirmed there were no known bugs, and generated a specific CLI-based troubleshooting guide.
Figure 4: The Output. Because of the strict persona settings, the AI provides specific commands (diagnose fdsm central-mgmt-status) rather than generic advice.
Conclusion
An undefined LLM is like a generalist intern: eager to please but often inaccurate. By defining a Persona and tuning the LLM, you transform that intern into a specialist.
Whether you are writing a comedy sketch or debugging a Layer 3 switch, the rule remains the same: The quality of the answer depends on who you ask. So when you Gemini “who’s on first,” make sure you know who is responding—it might just be Third Base.
Michael Elias is a Senior Principal Operations Engineer at Dun & Bradstreet with a history of entrepreneurship in the ISP and consulting spaces. A veteran of the dot-com era with certifications from Cisco, Red Hat, and Fortinet, Michael specializes in high-compliance infrastructure and enterprise architecture.
- Michael Elias (Read full bio)
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