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System Prompt Configuration

Configure how your Dexto agent behaves and responds through system prompts that define personality, capabilities, and guidelines.

Complete Reference

For complete field documentation and all configuration options, see agent.yml → System Prompt.

Overview​

System prompts define your agent's personality, behavior, and capabilities. They serve as the foundational instructions that guide how your agent interprets and responds to user requests.

You can use either a simple string for basic scenarios or an advanced multi-contributor system for complex agents that need dynamic context, file-based instructions, or memory integration.

Key capabilities:

  • Static instructions for consistent behavior
  • Dynamic context (date/time, MCP resources)
  • File-based documentation inclusion
  • Priority-based content ordering
Memory Configuration

For user memory integration, use the top-level memories configuration instead of system prompt contributors.

Configuration Types​

Simple String Prompt​

For straightforward agents, use a single string:

systemPrompt: |
  You are a helpful AI assistant with access to tools.
  Use these tools when appropriate to answer user queries.
  After each tool result, determine if you need more information or can provide a final answer.

Advanced Multi-Contributor System​

For complex scenarios requiring multiple content sources:

systemPrompt:
  contributors:
    - id: core-behavior
      type: static
      priority: 1
      content: |
        You are a professional software development assistant.
        You help with coding, documentation, and project management.

    - id: current-time
      type: dynamic
      priority: 10
      source: dateTime

    - id: project-docs
      type: file
      priority: 20
      files:
        - "${{dexto.agent_dir}}/README.md"
        - "${{dexto.agent_dir}}/CONTRIBUTING.md"
      options:
        includeFilenames: true
        errorHandling: "skip"

# Memory is configured separately at the top level
memories:
  enabled: true
  limit: 10

Contributor Types​

Static Contributors​

Fixed text content for consistent instructions.

- id: guidelines
  type: static
  priority: 1
  content: |
    Always be helpful, respectful, and thorough.
    Provide step-by-step solutions when possible.

Dynamic Contributors​

Runtime-generated content:

  • dateTime - Current date and time context
  • resources - MCP server resources (disabled by default)
- id: timestamp
  type: dynamic
  priority: 10
  source: dateTime
  enabled: true

File Contributors​

Include external documentation files (.md and .txt only):

- id: project-context
  type: file
  priority: 20
  files:
    - "${{dexto.agent_dir}}/docs/guidelines.md"
    - "../README.md"
  options:
    includeFilenames: true
    separator: "\n\n---\n\n"
    maxFileSize: 50000

Path resolution: Relative paths are resolved from the config file location.

Priority Ordering​

Contributors execute in ascending priority order (1 → 100+). Lower numbers appear first in the final system prompt.

Recommended ranges:

  • 1-10: Core behavior and role definition
  • 10-50: Dynamic context (time, resources)
  • 50-100: File-based documentation
  • 100+: Additional context and overrides

Use Cases​

ScenarioRecommended Approach
Simple chatbotSingle string prompt
Development assistantStatic + File contributors for guidelines
Customer supportStatic + top-level memories config
Research agentStatic + Dynamic (resources) for live data
Personal assistantStatic + File + Dynamic + memories config

Examples​

Production Agent​

systemPrompt:
  contributors:
    - id: core
      type: static
      priority: 1
      content: |
        You are a helpful AI assistant designed to work with tools and data.
        Provide clear, accurate responses and use available tools effectively.
    - id: timestamp
      type: dynamic
      priority: 10
      source: dateTime

Customer Support Agent​

systemPrompt:
  contributors:
    - id: role
      type: static
      priority: 1
      content: |
        You are a customer support assistant.
        Always be polite, professional, and solution-oriented.

memories:
  enabled: true
  limit: 10

Best Practices​

  1. Keep it focused - Clear, specific instructions work better than lengthy prompts
  2. Use priority ordering - Structure from general (role) to specific (context)
  3. Test behavior - Validate that prompts produce desired agent responses
  4. File contributors for docs - Keep large documentation in separate files
  5. Enable resources selectively - MCP resources can be large; only enable when needed
  6. Use top-level memories - Configure memory retrieval via the memories config field

See Also​