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Subagents are available in Firebender version 0.13.7 and later.
Custom subagents in Firebender are specialized AI assistants that can be invoked to handle specific types of tasks. They enable more efficient problem-solving by providing task-specific configurations with customized system prompts, tools and a separate context window.

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What are subagents?

Subagents are pre-configured AI personalities that Firebender can delsayegate tasks to. Each subagent:
  • Has a specific purpose and expertise area
  • Uses its own context window separate from the main conversation
  • Can be configured with specific tools it’s allowed to use
  • Includes a custom system prompt that guides its behavior
When Firebender encounters a task that matches a subagent’s expertise, it can delegate that task to the specialized subagent, which works independently and returns results.

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File format

Each subagent is defined in a Markdown file with this structure: 
---
name: your-sub-agent-name
description: Description of when this subagent should be invoked
tools: tool1, tool2, tool3 # Optional - inherits all tools if omitted
model: haiku # Optional - specify model alias
---

Your subagent's system prompt goes here. This can be multiple paragraphs
and should clearly define the subagent's role, capabilities, and approach
to solving problems.

Include specific instructions, best practices, and any constraints
the subagent should follow.

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Configuration fields

FieldRequiredDescription
nameYesUnique identifier using lowercase letters and hyphens
descriptionYesNatural language description of the subagent’s purpose
toolsNoComma-separated list of specific tools. If omitted, inherits all tools from the main thread
modelNoModel to use for this subagent. Can be a model alias (sonnet, opus, haiku). If omitted, defaults to the configured subagent model

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Available tools

You can configure subagents with any of the following tools:
  • read_file - Read files from the codebase
  • list_dir - List directory contents
  • grep_search - Search file contents with regex patterns
  • file_search - Fuzzy search for files by path
  • delete_file - Delete files
  • run_terminal_cmd - Execute terminal commands
  • web_search - Search the web for information
  • edit_file - Edit files in the codebase

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File locations

Subagents are stored as Markdown files with YAML frontmatter in two possible locations:
TypeLocationScopePriority
Project subagents.firebender/agents/Available in current projectHighest
User subagents~/.firebender/agents/Available across all projectsLower
When subagent names conflict, project-level subagents take precedence over user-level subagents.
  • Agent - Learn about Firebender’s agent modes
  • Commands - Custom AI commands for your exact workflow
  • MCP - Extend Firebender with Model Context Protocol