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Configuring an agent: system prompt and model

The agent configurator in depth: system prompt, model choice, parameters, and an advanced mode for power users.

2 min readUpdated 2026-07-07

The configurator is where an agent gets its character. You set the system prompt, model, and parameters here. There's a simple mode (the key settings) and an advanced one for fine control.

System prompt

The system prompt is the single most influential setting. A few principles for a good one:

  • Role in one line: "You are a financial advisor for self-employed in the US."
  • Output format: "Reply briefly, in bullets, with numbers."
  • Boundaries: what the agent must not do ("don't give legal guarantees").
  • Context: stable facts — audience, tone, language.

Prompt edits usually change the result more than switching models.

Choosing a model

ModelWhen to pick
deepseek-v4-proTop quality and reasoning — the default for new agents
deepseek-v4-flashFast everyday tasks, dialogue
glm-5.2Strong general-purpose alternative

All of these are available over /v1/chat/completions; the DeepSeek models are also served on the Anthropic-compatible /anthropic/v1/messages endpoint. The full list is available via the developer API.

Parameters

  • Temperature — output creativity. Lower is steadier and drier, higher is more varied.
  • Max tokens — reply length cap. Affects token spend.
  • File operations flag — allows file operations where applicable.

Advanced mode

Advanced mode exposes a direct editor for the system prompt and all parameters. It's handy when you need precise control or are porting a ready prompt from another tool.

How to test changes

  1. Save the agent.
  2. Open the chat and ask a typical question.
  3. If the result isn't right — refine the prompt and repeat.

Prompt iterations usually beat model switches. Token spend on tests shows up in Usage.

Configuring an agent: system prompt and model | AgentHere