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Claude AI Introduction: Build Your First Useful Feature

Start with one job you can inspect

Claude is most useful when it handles the part of a workflow that is hard to express with ordinary rules: reading messy language, noticing intent, and suggesting a next step. It is much less useful when it is asked to own every decision. In this first lesson, it will sort one support ticket into a small set of queues. Your application will still decide what happens next.

That is a good first AI feature because it is narrow, observable, and easy to improve. You can read the ticket, see the model’s proposed label, compare it with a human’s judgement, and safely send uncertain cases for review. The same shape later applies to summarising notes, extracting a draft from a document, or preparing a reply for an agent.

The goal of this lesson: Build a tiny ticket-routing assistant that proposes a queue. It is not a chatbot, it cannot change customer data, and it never becomes the final decision-maker.

Give each part of the feature a clear job

Part What it does What it must not do
Your application Authenticates the user, fetches the ticket, validates the label, and stores the result. Hand credentials or authorization decisions to the model.
Claude Reads the ticket and proposes one allowed queue. Issue refunds, alter records, or invent a queue.
A person or existing workflow Reviews uncertain items and takes consequential actions. Assume a plausible answer is automatically correct.

The first feature in one line

Keep the first release deliberately boring. Boring systems are easier to test and easier to trust.
  1. Ticket arrives Your server receives normal application data.
  2. Claude proposes a queue The request contains only the text needed for that task.
  3. Code validates the proposal Unknown labels become review items, not guesses.
  4. Workflow continues A human or deterministic rule owns the real action.

What Claude should decide—and what it should not

Think of Claude as a capable colleague who can read a pile of unstructured notes quickly, not as a replacement for the rest of your application. It can recognise that “I was charged twice” belongs with billing even when the customer does not use your exact internal vocabulary. That judgement is valuable, but it remains a proposal.

Identity, permissions, money movement, database writes, and policy enforcement should stay in ordinary code. Those rules need predictable behavior, audit trails, and a safe failure mode. If the model returns an unexpected answer, your code should be able to say “this needs review” without breaking the customer experience.

  • Use Claude for interpretation, drafting, and classification.
  • Use application code for access checks, validation, and actions.
  • Treat every model response as untrusted input until your code checks it.

Choose a problem small enough to learn from

A common first mistake is to build “an assistant for our whole business.” That sounds exciting, but it gives you no clear definition of success. A ticket router has four labels, a known input, and a visible outcome. When it makes a poor choice, you can add a better example, refine the instruction, or expand the review path.

Start with a decision a person already makes repeatedly. Ask the people who do the work which examples are confusing, which labels are acceptable, and which cases must always be escalated. Their answers are more useful than a generic list of prompt-writing tips.

  • Pick one input, one bounded output, and one way to review it.
  • Collect real but safely redacted examples before you optimise wording.
  • Write down what a safe “I do not know” result looks like.

Read the first request like a normal API call

The Messages API request below has two pieces of instruction. The system instruction defines the job and the permitted labels. The user message carries the current ticket. Keeping those roles separate makes the request easier to review and helps prevent old ticket text from quietly changing your application rules.

Notice what is missing: no customer profile, no order history, no API key in source code, and no request to perform an action. Send the minimum context needed for the task. Extra data does not make a feature more professional; it increases the information you have to protect and test.

  • Keep credentials in environment configuration, never inside a browser bundle.
  • Give the model a bounded instruction and only the current task context.
  • Use a low-risk output first; add tools only after the basic request is evaluated.

Let your code be the final gate

A model can answer with an extra sentence, a misspelled label, or a reasonable category that your workflow does not support. That does not mean the model has failed; it means the application needs a boundary. Normalize the response, compare it with your allowed list, and direct anything else to a human queue.

This simple validation layer is one of the habits that separates a demo from a useful feature. Later lessons will show stricter structured-output contracts, but the principle starts here: models suggest; the application accepts, rejects, or requests review.

  • Keep the accepted values in code or configuration you control.
  • Record the proposed value separately from the final workflow state.
  • Prefer a visible review state to silently coercing an unknown answer.

Test the awkward tickets, not just the easy ones

A happy-path example is useful for checking that the wiring works. It does not tell you whether the feature is ready. Add short, realistic cases: a customer asking for two things, a ticket with no clear queue, an angry message with little detail, and text that tries to override the instruction. Decide the expected safe outcome before you look at the response.

For a first release, a tiny spreadsheet or Python list is enough. Compare the expected queue with the proposed queue, note ambiguous cases, and improve the instruction only when you can explain why. This is slower than chasing a perfect prompt, but it produces something a team can maintain.

  • Use examples from the work, with personal information removed.
  • Include ambiguous and no-answer cases in every evaluation set.
  • Measure whether the review path catches uncertainty, not only exact matches.

You now have the right foundation

If you can make this small classifier work, you already understand the important shape of a reliable Claude feature: a narrow task, minimal context, a model proposal, code-side validation, and a way to learn from mistakes. The later lessons build on that foundation instead of replacing it.

Next, set up the client cleanly and make a first request in your own project. Do not rush to add a conversational interface or autonomous actions. Make one useful decision dependable first; the larger experience can grow around it.

Build the ticket router step by step

1. Create a small local project

Use a virtual environment so this experiment stays separate from the rest of your machine. Keep the API key in your environment; the client reads it when it starts.

1. Create a small local project
python -m venv .venv
.venv\Scripts\activate
pip install anthropic
set ANTHROPIC_API_KEY=your_key_here
set CLAUDE_MODEL=your_model_id
  • On macOS or Linux, activate with source .venv/bin/activate and export the variables instead of using set.
  • Do not commit a real key or a copied .env file to version control.

2. Ask Claude to propose one queue

This is intentionally small. The request sends one ticket and asks for exactly one of four allowed labels.

2. Ask Claude to propose one queue
import os

from anthropic import Anthropic

client = Anthropic()
response = client.messages.create(
    model=os.environ["CLAUDE_MODEL"],
    max_tokens=40,
    system=(
        "Sort support tickets into one label: billing, technical, account, or other. "
        "Reply with the label only."
    ),
    messages=[
        {
            "role": "user",
            "content": "I was charged twice for my monthly subscription.",
        }
    ],
)

proposal = response.content[0].text.strip()
print(proposal)
  • Use a current model ID that your account is allowed to call; keeping it in configuration avoids editing the program for each change.
  • The response is still a proposal. The next example decides whether your workflow accepts it.

3. Validate the label before using it

Small validation code turns unexpected model text into a safe review state instead of an accidental new queue.

3. Validate the label before using it
ALLOWED_QUEUES = {"billing", "technical", "account", "other"}

def route_ticket(proposal: str) -> str:
    label = proposal.strip().lower().rstrip(".")
    return label if label in ALLOWED_QUEUES else "needs_review"

print(route_ticket("Billing."))
print(route_ticket("urgent-refund"))
Output
billing
needs_review
  • In a production workflow, preserve the original proposal for debugging rather than overwriting it.

4. Store a proposal separately from the action

A record that distinguishes what the model suggested from what the workflow did makes review conversations much easier.

4. Store a proposal separately from the action
ALLOWED_QUEUES = {"billing", "technical", "account", "other"}

def route_ticket(proposal: str) -> str:
    label = proposal.strip().lower().rstrip(".")
    return label if label in ALLOWED_QUEUES else "needs_review"

def ticket_record(ticket_id: str, proposal: str) -> dict:
    route = route_ticket(proposal)
    return {
        "ticket_id": ticket_id,
        "model_proposal": proposal,
        "workflow_status": "queued" if route != "needs_review" else "review",
        "queue": route if route != "needs_review" else None,
    }

print(ticket_record("T-104", "mystery queue")["workflow_status"])
Output
review
  • The model has not performed a business action. It has supplied data for a workflow you control.

5. Keep a tiny evaluation set beside the prompt

Two examples are enough to establish the habit: decide the expected label first, then compare the returned proposal.

5. Keep a tiny evaluation set beside the prompt
ALLOWED_QUEUES = {"billing", "technical", "account", "other"}

def route_ticket(proposal: str) -> str:
    label = proposal.strip().lower().rstrip(".")
    return label if label in ALLOWED_QUEUES else "needs_review"

cases = [
    {"ticket": "I cannot reset my password", "expected": "account", "proposal": "account"},
    {"ticket": "The invoice shows an extra charge", "expected": "billing", "proposal": "billing"},
]

passed = sum(route_ticket(case["proposal"]) == case["expected"] for case in cases)
print(f"{passed} of {len(cases)} cases matched")
Output
2 of 2 cases matched
  • Add failures and edge cases to this list. They are the raw material for a better feature.
A strong first boundary

Before you continue

4 checks
  • I can state one small decision Claude is allowed to propose.
  • My application validates every accepted label against a list I control.
  • Sensitive or unrelated customer data stays out of the request.
  • An unexpected result goes to review instead of triggering an action.

Two beginner traps worth avoiding

  • Building a magical assistant first

    Start with one repeatable decision and a visible success measure. A small router that your team trusts is a better foundation than a broad assistant nobody can evaluate.
  • Treating fluent text as a system decision

    Keep authorization, validation, and consequential actions in application code. A confident sentence is not evidence that an operation is permitted.

Fifteen focused minutes

Make this lesson your own

0 of 3 completed

  1. Write down a task from your work that begins with messy text and ends with a small set of safe outcomes. Good candidates include routing, tagging, extracting a draft, or deciding whether a human should look next.
  2. Create two straightforward cases and one ambiguous case, with private details removed. Decide the expected outcome before using Claude. If there is no safe automatic outcome, make “needs_review” the expected result.
  3. Identify the exact function, person, or workflow that will validate the model proposal before anything consequential occurs. If you cannot name that gate, the first version is still too broad.

Questions people ask at the start

No. A focused feature such as classification, extraction, or draft preparation is usually a better first project because its outcome is easier to inspect and evaluate.

Send only the minimum data needed for the approved task and apply your organisation’s privacy, retention, and access rules. Do not send sensitive context merely because it might be useful.

A model can return extra text, a spelling variation, or an unsupported label. Validation gives your workflow a predictable safe response when that happens.

Next Step
Next Practice

Finish the concept here, then reinforce it with hands-on coding, interview prep, or a tool that matches the topic.

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