AI Prototype Prompt Engineering Product Architecture Concept to Deployment
Live experiment — active with a Toastmasters club

TM Evaluator
Assistant

An AI-powered speech evaluation companion for Toastmasters — built concept to working prototype in a single sprint, with a privacy-first design that keeps the human evaluator at the centre.

Role
Product Concept, Architecture,
Prompt Engineering, Deployment
Duration
Single sprint
Status
Live experiment
Monthly cost
~$0.15–0.30
Contents

The problem

Toastmasters clubs rely on member-to-member evaluations to help speakers grow. Evaluators listen to a speech and deliver structured verbal feedback. In practice, especially in smaller clubs, evaluators often struggle with:

Can AI assist evaluators without replacing the human connection that makes Toastmasters valuable?

The guiding principle

AI should elevate the Toastmasters experience, not replace it.

Toastmasters serves three core purposes — community, people connection, and practice. Any AI integration must preserve all three. The tool assists the evaluator. The evaluator still delivers the feedback. The speaker still receives it from a human who was in the room.

Key product decisions

Why an evaluator tool, not a speaker tool?
The initial instinct might be to build a tool that helps speakers practice. But that would pull activity away from the club meeting — the opposite of what a small club needs. By focusing on evaluators, the tool enhances the meeting experience itself. Better evaluations mean speakers get more value from attending, which improves retention.
Why live listening, not post-meeting analysis?
Evaluators deliver their feedback during the same meeting, usually within minutes of the speech. A tool that requires uploading a recording later misses the moment entirely. The tool needed to work in real-time, producing results fast enough for the evaluator to glance at before standing up.
Why no recording?
A non-negotiable design constraint driven by Toastmasters culture. Members speak in a safe, supportive environment. Introducing recordings — even temporary ones — changes the psychology of that space. The architecture was designed so audio is processed as a stream by the browser and never stored. Only the text transcript exists temporarily in memory, and it's cleared after analysis.
Why Pathways-aware evaluation?
Generic speech feedback is easy. What makes Toastmasters evaluation unique is that each speech has specific learning objectives tied to the speaker's Pathways project. An Ice Breaker speech should be evaluated differently than a Persuasive Speaking project. The tool dynamically adjusts its evaluation criteria based on which project the evaluator selects.

Architecture decisions

Speech-to-text: Browser Web Speech API

OptionAccuracyPrivacyCost
Browser Web Speech APIModerateAudio stays on-device*Free
Cloud API (Whisper / Deepgram)HighAudio sent to cloudPer-minute
Local model (Whisper.cpp)HighFully on-deviceFree

Browser Web Speech API was chosen for the prototype phase. It requires zero setup, costs nothing, and keeps the barrier to adoption as low as possible. Accuracy is sufficient because the AI analysis layer is robust enough to work with imperfect transcripts — it looks for patterns and themes, not word-for-word precision.

AI analysis: Claude Sonnet via Anthropic API

The evaluation requires nuanced understanding of Toastmasters culture — constructive framing, Commend, Recommend, Commend (CRC) structure, encouragement-first language. Sonnet provided the best balance of quality, speed (evaluators need results in under 10 seconds), and cost (~$0.03 per evaluation).

Prompt engineering as the core IP

The most valuable component of the system is not the code — it's the system prompt. This prompt encodes:

The prompt produces structured JSON output that the frontend renders into scannable talking points.

Security: serverless proxy for API key protection

A browser-based app calling an AI API directly would expose the API key in network requests. A lightweight serverless function sits between the browser and the API — the browser sends the transcript to the function, the function adds the API key (stored as a server-side environment variable) and forwards the request. The API key never touches the browser.

Access control: simple password gate

Rather than building user authentication, the app uses a single club access code. This provides a sense of security and prevents casual visitors from using the API credits, without the complexity of an auth system — appropriate for an experiment with a small, trusted group.

Data flow

Speaker's voice
    ↓
Phone microphone → Browser speech recognition (on-device)
    ↓
Text transcript (browser memory only)
    ↓
Evaluator taps "Done — Analyze"
    ↓
Transcript → Serverless proxy → AI API (encrypted)
    ↓
Structured evaluation (JSON) → Rendered as Commend, Recommend, Commend (CRC) talking points
    ↓
Transcript cleared from memory
    ↓
Tab closed → Everything gone

Key property: No data persists anywhere after the session. No database, no file storage, no cookies, no analytics tracking of speech content.

Pathways knowledge integration

The app contains a structured knowledge base of all six current Toastmasters Pathways with their levels and required projects. When an evaluator selects a pathway, level, and project, the system prompt is dynamically constructed to include the specific objectives for that project.

This means the same underlying AI produces different evaluation criteria for different speech types — an Ice Breaker evaluation focuses on self-introduction and personal storytelling, while a Persuasive Speaking evaluation focuses on evidence quality, emotional appeal, and call to action.

The knowledge base is structured as data (not hardcoded logic), making it straightforward to update when Toastmasters modifies their program.

Deployment and cost model

ComponentServiceCost
HostingNetlify (free tier)$0
Source controlGitHub (private repo)$0
Speech-to-textBrowser Web Speech API$0
AI evaluationAnthropic API (Claude Sonnet)~$0.03 / evaluation
Total for a small club~$0.15–0.30 / month

A $5 API credit sustains a small club for approximately 1.5–2 years. Usage tracking is handled through the hosting platform's built-in function invocation logs — each log entry represents one evaluation and one API call. No custom analytics infrastructure was needed.

Scaling considerations

ScaleEvaluations / monthEst. cost
1 club (experiment)4–8$0.15–0.30
4–5 clubs (Area)20–40$0.60–1.20
20+ clubs (Division)80–160$2.50–5.00
District-wide (200+ clubs)800+$25–50

The serverless architecture scales automatically — there's no server to upgrade. The cost scales linearly with usage. The constraint at scale is organizational (who manages the tool, who pays) rather than technical.

Key takeaways

1
The prompt is the product. In an AI-assisted tool, the most valuable intellectual property isn't the code — it's the prompt engineering that encodes domain expertise into the AI's behavior.
2
Privacy constraints drove better architecture. The "no recording" requirement forced a real-time, ephemeral design that is simpler, cheaper, and more trustworthy than alternatives that store data.
3
AI works best as a companion, not a replacement. The tool enhances human capability without removing the human from the loop. The evaluator remains the evaluator — the AI is a better notepad.
4
Domain knowledge matters more than model sophistication. A well-crafted prompt with the right Toastmasters context on a standard model outperforms a generic evaluation from a more powerful model without that context.
5
Start with the smallest viable experiment. One club, two evaluators, twice a month. The architecture supports scaling, but the learning comes from real-world usage at the smallest scale first.