picon-eval 0.1.3

Persona Interview & Consistency Evaluation Framework

PICON — Persona Interrogation framework for Consistency evaluation

---

An official Python package for evaluating LLM-based persona agents, called PICON. By running a multi-turn interview and fact-checking pipeline, you can measure how consistently and accurately a persona agent behaves. PICON evaluates persona agents across three dimensions:

• Internal Consistency: freedom from self-contradiction across answers.
• External Consistency: alignment of claims with real-world facts (via web search).
• Retest Stability: consistency of answers when the same questions are repeated within and across sessions.

 

Recent updates

• March 2026 (v0.1.0): Initial release with interview pipeline, evaluation, and CLI.

 

 

Installation

pip install picon-eval

import picon
print(picon.__version__)

For development or full extras (CharacterAI, Google GenAI, etc.):

git clone https://github.com/willystumblr/picon.git
cd picon
pip install -e ".[all]"

 

 

Quick Starts

[!NOTE] Before using PICON, you must provide API keys either directly or in a .env file.

• OpenAI models (gpt-*): Set OPENAI_API_KEY in your .env file.
• Gemini models (gemini/*): Set GEMINI_API_KEY in your .env file.
• Web search (external verification): Set SERPER_API_KEY in your .env file. Get one at serper.dev.

 

Environment Variables

Create a .env file in your working directory:

# LLM API Keys (at least one required)
OPENAI_API_KEY="YOUR_OPENAI_KEY"
GEMINI_API_KEY="YOUR_GEMINI_KEY"

# Web Search (required for external verification)
SERPER_API_KEY="YOUR_SERPER_KEY"

# Address validation (required for external verification)
GOOGLE_GEOCODE="YOUR_GOOGLE_GEOCODE_KEY"

# Optional
ANTHROPIC_API_KEY="YOUR_ANTHROPIC_KEY"
GOOGLE_CLAIM_SEARCH="YOUR_GOOGLE_API_KEY"       # Fact-check search
GOOGLE_CX_ID="YOUR_CUSTOM_SEARCH_ENGINE_ID"     # Custom Search Engine ID

 

Component-Based Usage

Import individual components and compose your own simulation pipeline:

from picon import Questioner, EntityExtractor, Evaluator, Interviewee
from picon import InterrogationSimulation

# Set up agents
questioner = Questioner(model="gpt-5")
extractor = EntityExtractor(model="gpt-5.1")
evaluator = Evaluator(model="gemini/gemini-2.5-flash")

# Set up the persona to evaluate
interviewee = Interviewee(
    model="gpt-5",
    persona="You are a 35-year-old software engineer living in Seoul.",
    name="John",
)

# Run the full interview + evaluation pipeline
sim = InterrogationSimulation(
    interviewee=interviewee,
    questioner=questioner,
    extractor=extractor,
    evaluator=evaluator,
    num_turns=20,
    num_sessions=2,
)
result = sim.run(do_eval=True)

print(result.eval_scores)
result.save("results/john.json")

# Example output:
# {
#     "internal_harmonic_mean": 0.82,
#     "external_ec": 0.75,
#     "inter_session_stability": 0.68,
#     "intra_session_stability": 0.91,
# }

With default agent models, you can omit agent setup entirely:

from picon import Interviewee, InterrogationSimulation

interviewee = Interviewee(model="gpt-5", persona="You are ...", name="John")
result = InterrogationSimulation(interviewee=interviewee, num_turns=20).run()

 

Evaluate an LLM Persona (Simple API)

For quick evaluations, use the picon.run() shortcut:

import picon

result = picon.run(
    model="gpt-5",
    persona="You are a 35-year-old software engineer living in Seoul.",
    name="John",
    num_turns=20,
    num_sessions=2,
    do_eval=True,
)

print(result.eval_scores)
result.save("results/john.json")

# Equivalent CLI command
picon --agent_model gpt-5 \
      --agent_persona "You are a 35-year-old software engineer living in Seoul." \
      --agent_name "John" \
      --num_turns 20 --num_sessions 2 --do_eval

 

Evaluate an External Agent Endpoint

If you already have a persona agent running (e.g. a wrapping server, fine-tuned model, RAG agent), provide its OpenAI-compatible endpoint URL (/v1/chat/completions).

from picon import Interviewee, InterrogationSimulation

interviewee = Interviewee(api_base="http://localhost:8000/v1", name="MyAgent")
result = InterrogationSimulation(interviewee=interviewee, num_turns=20).run()

# Equivalent CLI command
picon --agent_api_base http://localhost:8000/v1 \
      --agent_name "MyAgent" \
      --num_turns 20 --num_sessions 2 --do_eval

 

Self-hosted Models (vLLM)

For self-hosted models, provide both api_base and model:

from picon import Interviewee, InterrogationSimulation

interviewee = Interviewee(
    api_base="http://localhost:8000/v1",
    model="meta-llama/Llama-3-8B",
    persona="You are a 30-year-old teacher named Jane...",
    name="Jane",
)
result = InterrogationSimulation(interviewee=interviewee).run()

picon --agent_api_base http://localhost:8000/v1 \
      --agent_model meta-llama/Llama-3-8B \
      --agent_persona "You are a 30-year-old teacher named Jane..." \
      --agent_name "Jane" --do_eval

 

Separate Interview and Evaluation

import picon

# Step 1: Interview only
interview_result = picon.run_interview(
    name="John",
    model="gpt-5",
    persona="You are a 35-year-old software engineer...",
    num_turns=20,
    num_sessions=2,
)

# Step 2: Evaluate
persona_stats = picon.run_evaluation(interview_result, eval_factors=["internal", "external"])
print(persona_stats)

Evaluate an Existing Result File

scores = picon.evaluate("results/john.json", eval_factors=["internal", "external"])

 

 

Connecting an External Agent

PICON can evaluate any persona agent that exposes an OpenAI-compatible chat completions endpoint (POST /v1/chat/completions). If your agent already serves this endpoint (e.g. vLLM or any OpenAI-compatible server), just pass the URL directly — no wrapping needed.

 

Case 1: Your agent already has an OpenAI-compatible endpoint

If you're serving a model via vLLM or any server that implements /v1/chat/completions:

import picon

result = picon.run(
    api_base="http://<your-server-ip>:8000/v1",
    name="Alice",
    do_eval=True,
)

picon --agent_api_base http://<your-server-ip>:8000/v1 \
      --agent_name "Alice" --do_eval

 

Case 2: Your agent has custom logic (RAG, API calls, etc.)

If your agent doesn't have an OpenAI-compatible endpoint, wrap it with a simple server. You only need to implement one endpoint that accepts messages and returns a response:

import time
from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse
import uvicorn

app = FastAPI()

def generate_response(messages: list) -> str:
    """Replace this with your own agent logic."""
    user_message = messages[-1]["content"]
    # ... your custom logic (RAG retrieval, API call, etc.) ...
    return "This is my response."

@app.post("/v1/chat/completions")
async def chat_completions(request: Request):
    body = await request.json()
    messages = body.get("messages", [])

    content = generate_response(messages)

    return {
        "id": f"chatcmpl-{int(time.time())}",
        "object": "chat.completion",
        "created": int(time.time()),
        "model": "my-agent",
        "choices": [{
            "index": 0,
            "message": {"role": "assistant", "content": content},
            "finish_reason": "stop",
        }],
        "usage": {"prompt_tokens": 0, "completion_tokens": 0, "total_tokens": 0},
    }

if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8001)

Then evaluate with PICON:

picon --agent_api_base http://<your-server-ip>:8001/v1 \
      --agent_name "MyAgent" --do_eval

See examples/ for full end-to-end scripts with vLLM + LoRA and HumanSimulacra RAG

 

 

How It Works

1. Get-to-Know        Ask predefined demographic questions (WVS dataset)
       |
2. Main Interrogation Each turn runs this agent chain:
       |
       |-- Questioner    Generate the next question based on conversation history
       |-- Interviewee   The persona under evaluation answers the question
       |-- Extractor     Pull out entities and verifiable claims from the answer
       |-- Web Search    Fact-check extracted claims against the web
       '-- Evaluator     Compare this answer with previous answers for consistency
       |
3. Repeat Phase        Re-ask the get-to-know questions to measure stability
       |
4. Finalize            Compute all evaluation scores and save results

 

 

API Reference

Component Classes

Interviewee(model, persona, name, api_base, api_key):

• model (str): LLM model name. Required if api_base is not provided.
• persona (str): System prompt or path to a .txt file. Default: "".
• name (str): Interviewee display name. Default: "Agent".
• api_base (str): OpenAI-compatible endpoint URL. Required if model is not provided.
• api_key (str): API key for the endpoint. Default: None.

Questioner(model, prompt_path) / EntityExtractor(model, prompt_path) / Evaluator(model, prompt_path) / WebSearch(model, prompt_path):

• model (str): LLM model name. Each agent has its own default (see below).
• prompt_path (str): Custom system prompt file. None uses the built-in prompt.

InterrogationSimulation(interviewee, questioner, extractor, web_search, evaluator, ...):

• interviewee (Interviewee): The persona agent to evaluate. Required.
• questioner (Questioner): Questioner agent. None creates one with default model.
• extractor (EntityExtractor): Extractor agent. None creates one with default model.
• web_search (WebSearch): Web search agent. None creates one with default model.
• evaluator (Evaluator): Evaluator agent. None creates one with default model.
• num_turns (int): Interview turns per session. Default: 30.
• num_sessions (int): Number of repeated sessions. Default: 2.
• nhd_model (str): Model for AI detection. Default: "gpt-5-nano".
• output_dir (str): Output directory. Default: "data/results".
• question_seed (int): Random seed for question selection. Default: 42.

 

Simple API

picon.run() / picon.run_interview() Parameters:

• name (str): Interviewee name. Default: "Agent".
• model (str): LLM model name (e.g. "gpt-5", "gemini/gemini-2.5-flash"). Required if api_base is not provided.
• persona (str): System prompt or path to a .txt file. Default: "".
• api_base (str): OpenAI-compatible API endpoint URL. Required if model is not provided.
• api_key (str): API key for the persona endpoint. Default: None.
• num_turns (int): Number of interview turns. Default: 30.
• num_sessions (int): Number of repeated sessions. Default: 2.
• do_eval (bool): Run evaluation after interview. Default: True.
• eval_factors (list): Evaluation factors to run: "internal", "external", "intra", "inter". Default: None (all).
• questioner_model (str): Model for the questioner agent. Default: "gpt-5".
• extractor_model (str): Model for the entity extractor agent. Default: "gpt-5.1".
• web_search_model (str): Model for the web search agent. Default: "gpt-5".
• evaluator_model (str): Model for the evaluator agent. Default: "gemini/gemini-2.5-flash".
• nhd_model (str): Model for AI detection. Default: "gpt-5-nano".
• output_dir (str): Output directory for results. Default: "data/results".
• question_seed (int): Random seed for question selection. Default: 42.

 

 

Evaluation Metrics

Metric	Description
Internal Responsiveness	Relevance of answers to questions
Internal Consistency	Consistency of answers to repeated questions
Internal Harmonic Mean	Harmonic mean of Responsiveness and Consistency
External Coverage	Fraction of turns containing at least one verifiable claim
External Non-refutation Rate	Per-turn rate of claims not refuted by web evidence
External Consistency (EC)	Harmonic mean of Coverage and Non-refutation Rate
Inter-session Stability	Answer stability across sessions
Intra-session Stability	Answer stability within a session

 

 

Examples

End-to-end scripts in examples/:

# OpenCharacter (vLLM + LoRA)
python examples/test_opencharacter_vllm.py

# HumanSimulacra (RAG agent)
python examples/test_human_simulacra.py
python examples/test_human_simulacra.py --character "Kevin Kelly" --model "gpt-5"

 

 

Citation

If you use PICON in your research, please cite:

@article{kim2026picon,
  title={PICON: A Multi-Turn Interrogation Framework for Evaluating Persona Agent Consistency},
  author={Kim, Minseo and Im, Sujeong and Choi, Junseong and Lee, Junhee and Shim, Chaeeun and Choi, Edward},
  journal={arXiv preprint arXiv:2603.25620},
  year={2026}
}