AI Agent vs
Custom GPT

Understand the difference, choose the right tool, and build with confidence.

01

Side-by-side comparison

Custom GPT
Guided, prompt-driven assistant
Lower complexity
Autonomy
Low β€” follows instructions only
Tool use
Limited β€” web search, image gen, files
Memory
Within-session + uploaded files only
Setup time
30 min – 2 hours (no code)
Risk level
Low
AI Agent
Autonomous, multi-step executor
Higher complexity
Autonomy
High β€” plans and acts independently
Tool use
Extensive β€” APIs, databases, browsers, code
Memory
Persistent across sessions + external stores
Setup time
Days to weeks (dev + testing needed)
Risk level
High β€” requires guardrails
02

Concrete examples

What a Custom GPT can do
Answer HR policy questions using an uploaded employee handbook
Generate social media captions in your brand voice from a brief
Create first drafts of audit reports following a fixed template
Summarise lengthy policy documents into plain-language summaries
Coach users through an accessibility checklist step by step
What an AI agent can do
Monitor a mailbox, classify emails, draft responses, and file them automatically
Scrape tender portals daily, score opportunities, and populate a CRM
Run an end-to-end grant application β€” research, drafting, submission tracking
Conduct nightly competitor analysis and push a digest to Slack by 7am
Audit a live website for WCAG violations and generate a remediation log
03

Decision filter β€” by use case

πŸ’¬ Custom GPT
Best for templated formats: newsletters, captions, reports
Maintains consistent brand voice you define in the system prompt
Lets your team self-serve content without technical skills
Recommended for most content teams
πŸ€– AI agent
Use when content must be sourced, researched, and published automatically
Ideal for full pipelines: research β†’ draft β†’ SEO check β†’ CMS upload
Overkill for manual, human-reviewed content at small volume
Use for high-volume automated pipelines
πŸ’¬ Custom GPT
Can guide a human through a workflow step by step
Cannot trigger external systems or take actions autonomously
Works well as a smart form or decision-tree replacement
Use as a guided assistant, not an executor
πŸ€– AI agent
Directly connects to APIs, databases, and third-party tools
Can run multi-step workflows end to end with full error handling
Requires careful scoping, testing, and human oversight triggers
Strongly recommended for automation
πŸ’¬ Custom GPT
Excellent for synthesising uploaded documents into insights
Can do live web search within a session (with browsing enabled)
Limited to the session β€” no persistent research memory
Great for ad-hoc document research
πŸ€– AI agent
Can run continuous, scheduled research across multiple sources
Stores findings in a knowledge base and updates it over time
Can cross-reference sources, flag contradictions, and rank findings
Best for ongoing structured research programmes
04

Recommendation engine

Answer five questions and get a personalised tool recommendation with a rationale. All five answers are needed before a result appears.

Does the task need to run without a human present?

Does it need to connect to external systems (email, CRM, databases)?

How quickly do you need this up and running?

What is your team's technical capacity?

Will this AI tool make decisions that affect people?

β™Ώ Accessibility Compliance Note
Standards applied: WCAG 2.0 / 2.1 / 2.2 Level AAA + Universal Design Principles (all 7).
Key measures: Semantic HTML5 landmark structure; logical heading hierarchy (h1 β†’ h2); skip navigation link; keyboard navigability on all interactive controls with visible focus indicators (3px outline); ARIA roles, labels, and live regions throughout; colour contrast exceeds 7:1 on all text; information not conveyed by colour alone (bars, dots, and text labels used together); responsive layout reflows at 320px minimum width; prefers-reduced-motion support; screen-reader-friendly tab panels with aria-selected states; progressbar for 5-question recommendation engine; all interactive buttons labelled with aria-checked states.
Known limitations: Emoji used as decorative icons are marked aria-hidden where they are purely illustrative. No known AAA violations for this deliverable.