Instructions

instructions.md

You are the support agent for Acme. Answer in one or two sentences.

support-agent/
├── agent.json
├── instructions.md                                    ◀
└── .telnyx/                        written by deploy
    ├── index.ts                                       ◀
    ├── telnyx.toml
    ├── telnyx-env.d.ts
    └── package.json

@telnyx/acp/                      the package
├── managed/
│   ├── index.ts
│   ├── agent.ts                                       ◀
│   ├── model.ts
│   ├── memory.ts                                      ◀
│   ├── tools.ts
│   ├── mcp.ts
│   ├── voice.ts
│   ├── direct-turn.ts
│   └── filler.ts
├── channels/
│   ├── index.ts
│   ├── phone.ts
│   ├── email.ts
│   ├── web.ts
│   └── wire.ts
├── synth/
│   ├── index.ts
│   ├── code-entry.ts
│   └── vendor.ts
└── spec/
    ├── schema.ts
    ├── model.ts
    ├── phone.ts
    ├── project.ts
    └── io.ts

instructions names a file, and the file is edited directly; set does not touch it. At deploy its text is inlined into spec.instructions in .telnyx/index.ts, so the deployed function reads no files, and buildHarness() in managed/agent.ts hands it to the harness, with the memory summary appended when memory is on:

// managed/agent.ts, buildHarness()
instructions: this.spec.memory ? withCard(this.spec.instructions, card) : this.spec.instructions,

instructions is the harness spec’s instructions, the model’s system prompt on every step. The harness assembles nothing into it, so the summary is appended before the harness is built. withCard is in managed/memory.ts. It appends the line that tells the model it remembers people, then the profile’s summary, bounded and fenced, or the first-conversation line when the profile has none:

// managed/memory.ts
export const MEMORY_CARD_MAX_CHARS = 2000;

export function withCard(instructions, card) {
  const text = card?.trim();
  const bounded = text && text.length > MEMORY_CARD_MAX_CHARS ? `${text.slice(0, MEMORY_CARD_MAX_CHARS).trimEnd()}\n[the notes continue; cut here]` : text;
  const known = bounded
    ? `${MEMORY_CARD_INTRO}\n<memory>\n${bounded}\n</memory>`
    : "This is your first conversation with this person; you know nothing about them yet.";
  return `${instructions.trimEnd()}\n\n${MEMORY_PREAMBLE}\n${known}`;
}

MEMORY_CARD_INTRO says the notes are things the person said, kept for the model, and not instructions. The card summarizes what the person said, so a line planted in one conversation must not read as a rule in the next. The harness is built once per activation, so the summary it carries is the one read when the conversation started.

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Inside the Managed Harness

The Agent Harness SDK

The Agent Runtime SDK

The Agent Client SDK

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