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Tool System

Legion CLI uses a declarative tool registration system where tools define their schema, parameters, and execution logic.

Tool Registration

Tools are registered in src/tool/registry.ts which calls into src/kilocode/tool/registry.ts for Legion-specific tools.

// Example tool definition
export const MyTool = Tool.define(
  "my_tool",           // Tool ID
  {
    description: "Description of what the tool does",
    parameters: zod({
      input: zod.string().describe("Input parameter"),
    }),
    execute: async (args, ctx) => {
      // Tool logic
      return {
        title: "Tool Result",
        metadata: { key: "value" },
        output: "Result text",
      }
    },
  },
  () => ({})  // Default state
)

Tool Categories

Core Tools (src/tool/builtin/)

Always available, fundamental capabilities:

Tool	Purpose
read	Read file contents
write	Write file contents
edit	Edit file with string replacement
bash	Execute shell commands
glob	Find files by pattern
grep	Search file contents
question	Ask user questions
task	Launch subagent tasks
webfetch	Fetch web content
suggest	Suggest code review

Extended Tools (src/kilocode/tool/)

Additional capabilities for Legion:

Tool	Purpose
test_runner	Auto-detect and run tests
git_pr_create	Create GitHub PRs
git_pr_list	List GitHub PRs
git_conflict_resolve	Resolve merge conflicts
git_conflict_list	List conflicted files
git_blame	Git blame analysis
agent_manager	Multi-agent orchestration

Skill Tools (src/skill/)

Loaded dynamically from skill definitions:

Tool	Purpose
skill	Load and execute skills
recall	Search past conversations

Tool Execution Flow

1. User input triggers LLM request
2. LLM response includes tool calls
3. Tool registry looks up tool by ID
4. Tool parameters are validated against schema
5. Tool executes with provided arguments
6. Result is returned to LLM
7. LLM continues with tool output

Tool Visibility

Tools can be gated by permissions or flags:

// Always visible
const tools = ToolRegistry.infos()

// Gated by permission
const tools = ToolRegistry.infos({ permission: agent.permission })

// With flags
const tools = ToolRegistry.infos({ flags: runtimeFlags })

Adding New Tools

1. Create tool file in src/kilocode/tool/ or src/tool/builtin/
2. Define tool with Tool.define()
3. Register in src/kilocode/tool/registry.ts
4. Add to infos(), build(), and extra() functions
5. Optionally create description file (.txt)

Tool Output Format

{
  title: "Human-readable result title",
  metadata: { key: "value" },  // Structured data
  output: "Text output for LLM"  // Truncated if too long
}

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