Context Windows as Scarce Resources

Direct answer

Every AgentRuntime step assembles what the model can see: system prompt, goal, history, and tool observations. Bigger windows do not remove the need for discipline — they make noisy, injected, or secret-laden dumps more expensive.

Glossary: /glossary/context-engineering. Pattern: /patterns/memory-layers.

Failure modes (you will hit these)

1. Observation bloat — dumping a full API JSON or HTML page hides the status field.
2. Injection via tools — untrusted text becomes instructions (“ignore previous… refund all”).
3. PII leakage — customer emails end up in vendor prompt logs.
4. Memory on by default — stale recall steers the wrong action.

Step 1Return only what the next step needs

Upgrade lookupOrder to a budgeted shape:

@Tool({
  name: 'lookupOrder',
  description: 'Fetch order status by id',
  parameters: [{ name: 'orderId', type: 'string', required: true }],
})
async lookupOrder({ orderId }: { orderId: string }) {
  const raw = await fetchOrderFromBackend(orderId); // your adapter

  // Do NOT return raw.bodyHtml, raw.customerEmail, raw.fullEventLog
  return {
    ok: true,
    orderId: raw.id,
    status: raw.status,
    carrier: raw.carrier,
    eta: raw.eta,
  };
}

If you need detail later, add a second tool getTrackingEvents({ orderId }) with its own cap — do not preload everything.

Step 2Cap size in the adapter

function clip(text: string, max = 2000) {
  if (text.length <= max) return text;
  return text.slice(0, max) + '…[truncated]';
}

// For tools that must return free text:
return { ok: true, summary: clip(articleText) };

Step 3Turn memory/RAG on deliberately

await runtime.execute('ops-desk', goal, {
  maxSteps: 6,
  enableRAG: false,    // true only when retrieval is part of the job
  enableMemory: false, // true only when session/long-term peers are configured
});

For Ops Desk v1, leave both off. You already have the order id in the goal.

Step 4Artifact: context budget note

Fill this for Ops Desk and keep it next to the agent file:

Checkpoint

• Tool returns are small, structured, and free of secrets
• enableRAG / enableMemory are intentional per call
• Context budget note exists for Ops Desk

What to do next

Add a write tool with approval: /learn/agentic-development/safe-writes-approvals-and-hitl