oneshot

oneshot is the simplest possible pattern: one LLM call, no tools, no loop.

The agent’s system prompt comes from the AGENT.md body. The input is passed directly as the user message. The LLM response is the output.

When to use it

• Text transformations (summarize, translate, reformat)
• Classification or labeling
• Generating short content (titles, descriptions, tags)
• Any task that needs a single focused LLM response

AGENT.md

---
name: summarizer
description: Summarizes text concisely.
version: "1.0.0"
pattern: oneshot
call:
  model:
    role: thinker
---

You are a concise summarizer. Given any text, return a clear 2-3 sentence summary.
Focus on the key insights. Do not pad the response.

Scaffold

tama add oneshot my-agent

How it works

1. Input is received as the user message
2. System prompt is the AGENT.md body
3. Single LLM call is made
4. LLM response is returned with key="result"

No start(), no finish(), no tools. The runtime handles everything.

Output

The output key is always "result". When used as a step inside an fsm, the FSM transitions unconditionally from oneshot agents (since they always produce the same key).

Step file variant

When used as a step inside critic, reflexion, or other multi-step patterns, each step file can declare oneshot behavior implicitly — the step is a single LLM call with the step file’s body as the system prompt.

Configuration

call:
  model:
    role: thinker          # use role-based model selection
    temperature: 0.0       # deterministic output
    max_tokens: 512        # short response

Example: essay title generator

---
name: title-generator
description: Generates a compelling title for an essay.
version: "1.0.0"
pattern: oneshot
call:
  model:
    role: writer
    temperature: 0.9
---

Generate a single compelling, specific title for the following essay.
Return only the title, no explanation, no quotes.

Run:

tama run "Rust's borrow checker enforces memory safety at compile time..."

Output:

The Compile-Time Memory Safety Guarantee: How Rust's Borrow Checker Changed Systems Programming