04-permissions-and-tool-controls.md

layout	default
title	Chapter 4: Permissions and Tool Controls
nav_order	4
parent	Crush Tutorial

Chapter 4: Permissions and Tool Controls

Welcome to Chapter 4: Permissions and Tool Controls. In this part of Crush Tutorial: Multi-Model Terminal Coding Agent with Strong Extensibility, you will build an intuitive mental model first, then move into concrete implementation details and practical production tradeoffs.

This chapter covers how to define safe execution boundaries without killing productivity.

Learning Goals

• set explicit tool-permission policies in Crush
• constrain high-risk tools and commands
• understand --yolo mode risks
• use ignore rules to reduce accidental context exposure

Permission Controls

Control	Location	Purpose
permissions.allowed_tools	config	allow safe tools to run without repeated prompts
options.disabled_tools	config	fully hide high-risk or irrelevant built-in tools
disabled_tools under MCP configs	config	disable specific MCP-exposed tools
--yolo	CLI flag	bypass prompts; use only in trusted environments

Practical Safety Baseline

1. default to prompts for write/destructive actions
2. disable tools not required for your current task class
3. use .crushignore to exclude large/noisy/sensitive paths
4. reserve --yolo for disposable sandboxes

Source References

• Crush README: Allowing Tools
• Crush README: Disabling Built-In Tools
• Crush README: Ignoring Files

Summary

You now have a practical control model for balancing Crush autonomy and safety.

Next: Chapter 5: LSP and MCP Integration

Depth Expansion Playbook

Source Code Walkthrough

internal/config/config.go

The IsConfigured function in internal/config/config.go handles a key part of this chapter's functionality:

}

// IsConfigured  return true if at least one provider is configured
func (c *Config) IsConfigured() bool {
	return len(c.EnabledProviders()) > 0
}

func (c *Config) GetModel(provider, model string) *catwalk.Model {
	if providerConfig, ok := c.Providers.Get(provider); ok {
		for _, m := range providerConfig.Models {
			if m.ID == model {
				return &m
			}
		}
	}
	return nil
}

func (c *Config) GetProviderForModel(modelType SelectedModelType) *ProviderConfig {
	model, ok := c.Models[modelType]
	if !ok {
		return nil
	}
	if providerConfig, ok := c.Providers.Get(model.Provider); ok {
		return &providerConfig
	}
	return nil
}

func (c *Config) GetModelByType(modelType SelectedModelType) *catwalk.Model {
	model, ok := c.Models[modelType]
	if !ok {

This function is important because it defines how Crush Tutorial: Multi-Model Terminal Coding Agent with Strong Extensibility implements the patterns covered in this chapter.

internal/config/config.go

The GetModel function in internal/config/config.go handles a key part of this chapter's functionality:

}

func (c *Config) GetModel(provider, model string) *catwalk.Model {
	if providerConfig, ok := c.Providers.Get(provider); ok {
		for _, m := range providerConfig.Models {
			if m.ID == model {
				return &m
			}
		}
	}
	return nil
}

func (c *Config) GetProviderForModel(modelType SelectedModelType) *ProviderConfig {
	model, ok := c.Models[modelType]
	if !ok {
		return nil
	}
	if providerConfig, ok := c.Providers.Get(model.Provider); ok {
		return &providerConfig
	}
	return nil
}

func (c *Config) GetModelByType(modelType SelectedModelType) *catwalk.Model {
	model, ok := c.Models[modelType]
	if !ok {
		return nil
	}
	return c.GetModel(model.Provider, model.Model)
}

This function is important because it defines how Crush Tutorial: Multi-Model Terminal Coding Agent with Strong Extensibility implements the patterns covered in this chapter.

internal/config/config.go

The GetProviderForModel function in internal/config/config.go handles a key part of this chapter's functionality:

}

func (c *Config) GetProviderForModel(modelType SelectedModelType) *ProviderConfig {
	model, ok := c.Models[modelType]
	if !ok {
		return nil
	}
	if providerConfig, ok := c.Providers.Get(model.Provider); ok {
		return &providerConfig
	}
	return nil
}

func (c *Config) GetModelByType(modelType SelectedModelType) *catwalk.Model {
	model, ok := c.Models[modelType]
	if !ok {
		return nil
	}
	return c.GetModel(model.Provider, model.Model)
}

func (c *Config) LargeModel() *catwalk.Model {
	model, ok := c.Models[SelectedModelTypeLarge]
	if !ok {
		return nil
	}
	return c.GetModel(model.Provider, model.Model)
}

func (c *Config) SmallModel() *catwalk.Model {
	model, ok := c.Models[SelectedModelTypeSmall]
	if !ok {

This function is important because it defines how Crush Tutorial: Multi-Model Terminal Coding Agent with Strong Extensibility implements the patterns covered in this chapter.

internal/config/config.go

The GetModelByType function in internal/config/config.go handles a key part of this chapter's functionality:

}

func (c *Config) GetModelByType(modelType SelectedModelType) *catwalk.Model {
	model, ok := c.Models[modelType]
	if !ok {
		return nil
	}
	return c.GetModel(model.Provider, model.Model)
}

func (c *Config) LargeModel() *catwalk.Model {
	model, ok := c.Models[SelectedModelTypeLarge]
	if !ok {
		return nil
	}
	return c.GetModel(model.Provider, model.Model)
}

func (c *Config) SmallModel() *catwalk.Model {
	model, ok := c.Models[SelectedModelTypeSmall]
	if !ok {
		return nil
	}
	return c.GetModel(model.Provider, model.Model)
}

const maxRecentModelsPerType = 5

func allToolNames() []string {
	return []string{
		"agent",
		"bash",

This function is important because it defines how Crush Tutorial: Multi-Model Terminal Coding Agent with Strong Extensibility implements the patterns covered in this chapter.

How These Components Connect

flowchart TD
    A[IsConfigured]
    B[GetModel]
    C[GetProviderForModel]
    D[GetModelByType]
    E[LargeModel]
    A --> B
    B --> C
    C --> D
    D --> E

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