Project Lion - Senior Prompt Engineer - Portugal (Remote, Part-Time)

Welo Global; United States; Remote; USD 78,000 - 112,000; Full time

Job summary

Welo Global in Portugal seeks a Prompt Engineer to lead the end-to-end migration workflow for transitioning templates to LLM autoraters, leveraging internal tools to maximize model performance.

You will run APG and APO systems, draft and refine prompts for complex template architectures, monitor edge cases, and quantify accuracy against gold data.

Strong Portuguese and English, a CS/DS-related degree, and 4+ years in prompt engineering are required.

Qualifications

• 4+ years of experience as Prompt Engineer.
• Proven experience tuning LLMs for structured outputs.
• Proficiency with SQL or related data analytics tools.
• Native Portuguese with fluent English.

Responsibilities

• Use APG tools to generate baseline prompts for template clusters.
• Run APO tool, review outputs, and flag deadlocks or plateaus.
• Draft and refine prompts to handle edge cases and anti-patterns.
• Monitor shadowbot runs and track disagreements between human and LLM ratings.
• Evaluate prompts against gold data, measuring accuracy metrics (F1, precision, recall).
• Prepare Launch Certification Documentation for readiness.

Skills

Portuguese (native)

English (fluent)

Data analysis

SQL

Communication

Fast learner

Prompt engineering

Education

Bachelor’s/Master’s/Doctorate in CS/DS/Computational Linguistics/HCI

Tools

APG tools

APO systems

Goose API

Job description

We are seeking a Prompt Engineer to be responsible for the end-to-end technical migration workflow for transitioning templates to LLMautoraters. The role is required to use client’s internal tools to leverage prompt engineering techniques to maximize model performance.

Responsibilities

• Utilize Automatic Prompt Generation (APG) tools to create baseline prompts for complex parent-child template clusters.
• Run and supervise Automated Prompt Optimization (APO) tool, review the outputs, and flag when the APO reaches deadlocks or plateaus.
• Manually draft, test, and refine prompts to navigate complex template architectures, overcome anti-patterns, and handle edge cases where tooling is lacking or broken. Solve edge-case scenarios by designing and refining manual prompts.
• Monitorshadowbotruns to ensure sufficient disagreements (between human and LLM ratings) are registered, generated, and tracked.
• Run prompt versions against established gold data to continuously measure autorater quality against the human crowd baseline, calculating accuracy metrics such as F1 scores, precision, and recall.
• Draft technical launch readiness justifications (Launch Certification Documentation) for final.

Requirements

• Language Skills: Native fluency in Portuguese and fluent in English.
• Location: Must be based in Portugal.
• Education: Bachelor’s, Master’s, or Doctorate degree in Computer Science, Data Science, Computational Linguistics, Human-Computer Interaction (HCI), Cognitive Science, ora relatedanalytical field.
• Prompt Engineering & AI Expertise: At least 4 years' experience as Prompt Engineer. Proven experience tuning Large Language Models (LLMs)for strict, structured outputs, complex classification tasks, and familiarity with chain-of-thought and few-shot learning.
• Data Analysis: Strongproficiencyinidentifyingerror patterns, analyzing model performance, and using SQL or other data analytics tools.
• Technical Agility: Ability to quickly learn and master proprietary tools with minimal supervision.
• Communication: Excellent verbal and written communication skills.

Optional / Preferred Skills

• Familiarity with enterprise-grade LLM interfaces like the Goose API.
• Experience in AI model evaluation, data science, computational linguistics, or software engineering.
• Hands-on experience with Automated Prompt Optimization (APO) systems or tuning workflows.
• Linguistic expertise, including an understanding of semantics and logic.

CompensationAdditional Information