amplifier-module-tool-slash-command

January 13, 2026 · View on GitHub

Extensible slash command system for Amplifier, enabling custom commands defined as Markdown files.

Overview

This module provides:

  • Custom slash commands as Markdown files with YAML frontmatter
  • Project-scoped commands (.amplifier/commands/)
  • User-scoped commands (~/.amplifier/commands/)
  • Template substitution for arguments ($ARGUMENTS, $1, $2, etc.)
  • Bash execution in templates (!command`` syntax)
  • File references (@path/to/file includes file content)
  • Granular permissions (Bash(git add:*) restricts which commands can run)
  • Command composition (commands can invoke other commands)
  • Model override (per-command model selection)
  • LLM discovery (AI can list and invoke commands programmatically)

Inspired by Claude Code's extensible slash command system, adapted for Amplifier's modular architecture.

Installation

As an Amplifier Module

Add to your bundle:

tools:
  - module: tool-slash-command
    source: git+https://github.com/microsoft/amplifier-module-tool-slash-command@main

Or install directly:

amplifier module add tool-slash-command \
  --source git+https://github.com/microsoft/amplifier-module-tool-slash-command@main

Usage

Creating Custom Commands

Create a Markdown file in .amplifier/commands/ (project) or ~/.amplifier/commands/ (personal):

Example: .amplifier/commands/review.md

---
description: Request comprehensive code review
allowed-tools: [read_file, grep, task]
argument-hint: [file-or-directory]
---

Please review {{\$1 or "recent changes"}} with focus on:
- Code quality and readability
- Potential bugs or edge cases
- Security vulnerabilities
- Performance considerations
- Best practices compliance

Using Commands

In the Amplifier REPL:

> /review src/auth.py
# Executes command with file argument

> /review
# Executes command with default (recent changes)

Command Discovery

The module automatically discovers commands from:

  1. .amplifier/commands/ (project-scoped, version controlled)
  2. ~/.amplifier/commands/ (user-scoped, personal)
  3. Git URL sources (shared command repos, configured in bundle)

Commands are registered when the session starts.

Git URL Command Sources

Share commands across projects by referencing git repositories in your bundle:

tools:
  - module: tool-slash-command
    source: git+https://github.com/microsoft/amplifier-module-tool-slash-command@main
    config:
      commands:
        - git+https://github.com/org/shared-commands@v1
        - git+https://github.com/team/review-tools@main

With subpath (commands in a subdirectory):

config:
  commands:
    - git+https://github.com/org/monorepo@main:amplifier-commands

Commands are lazily fetched - cloned and cached on first use to ~/.amplifier/cache/commands/.

Command repo requirements:

  • Must contain a .amplifier-commands marker file (can be in root or subpath)
  • Command .md files discovered recursively from that location

Example command repo structure:

shared-commands/
├── .amplifier-commands    # Marker file (can contain documentation)
├── review.md
├── deploy.md
└── team/
    └── standup.md

Precedence (highest to lowest):

  1. Project commands (.amplifier/commands/)
  2. User commands (~/.amplifier/commands/)
  3. Git URL commands (in order listed)

Command Format

Frontmatter Options

description: Brief description shown in /help
allowed-tools:                    # Tool restrictions (see Granular Permissions)
  - bash                          # Allow all bash commands
  - Bash(git status:*)            # Allow only specific bash commands
  - read_file                     # Allow specific tools
argument-hint: [arg1] [arg2]      # Shown in autocomplete
model: claude-3-5-haiku-20241022  # Override session model for this command
max-chars: 10000                  # Truncate output to character limit
requires-approval: true           # Require user confirmation before execution
approval-message: "This will..."  # Custom approval prompt
disable-model-invocation: true    # Hide from LLM discovery (user-only command)

Template Variables

  • $ARGUMENTS - All arguments as a single string
  • $1, $2, $3, ... - Individual positional arguments
  • {{\$1 or "default"}} - Variable with fallback value

Bash Execution

Execute shell commands during template processing:

Inline bash:

Current branch: !`git branch --show-current`

Block bash:

!```
git status --short
git log --oneline -5


**Requires** `bash` in `allowed-tools`. See Granular Permissions for fine-grained control.

### File References

Include file contents in templates:

```markdown
Review this code:
@src/main.py

Compare with:
@src/utils.py

Command Composition

Commands can invoke other commands:

---
description: Full project review
allowed-tools: [Bash(git status:*), Bash(git diff:*)]
---

## Git Status
/git-status

## Code Review
/review src/

Summarize the project state above.

Nested commands are executed and their output is substituted into the parent template. Maximum nesting depth: 5 levels (prevents infinite loops).

Granular Permissions

Control exactly which bash commands a slash command can execute:

allowed-tools:
  - Bash(git status:*)    # Only git status commands
  - Bash(git diff:*)      # Only git diff commands
  - Bash(git log:*)       # Only git log commands

Pattern matching:

  • Bash(git add:*) - Allows git add ., git add -A, git add file.txt
  • Bash(ls:*) - Allows ls, ls -la, ls /path

Security:

  • Commands not matching any pattern are blocked
  • Blocked commands show [Command blocked: reason] in output
  • Warnings are returned to the caller

Example - Safe git operations only:

---
description: Safe git status check
allowed-tools:
  - Bash(git status:*)
  - Bash(git diff:*)
  - Bash(git log:*)
---

!`git status`      # Allowed
!`git diff HEAD`   # Allowed
!`git push`        # BLOCKED - not in allowed patterns
!`rm -rf /`        # BLOCKED - not in allowed patterns

LLM Command Discovery (Skill Tool)

The LLM can discover and invoke commands programmatically:

List available commands:

result = await tools["slash_command"](operation="list")
# Returns: {"commands": [...], "count": N}

Execute a command:

result = await tools["slash_command"](
    operation="execute",
    command="review",
    args="src/auth.py"
)

Hiding commands from LLM:

Add disable-model-invocation: true to hide sensitive commands:

---
description: Admin-only command
disable-model-invocation: true
---

These commands won't appear in list and will be blocked if the LLM tries to execute them directly.

Model Override

Specify a different model for specific commands:

---
description: Quick answer using faster model
model: claude-3-5-haiku-20241022
---

Give a brief answer to: $ARGUMENTS

The model_override is returned in the tool result for the CLI/orchestrator to use.

Examples

Simple command:

---
description: Explain code in simple terms
---
Explain this code in simple, beginner-friendly terms: $ARGUMENTS

With bash and file refs:

---
description: Project context dump
allowed-tools: [bash]
---

## Git Status
!`git status --short`

## Recent Commits
!`git log --oneline -10`

## README
@README.md

With granular permissions:

---
description: Safe git operations
allowed-tools:
  - Bash(git status:*)
  - Bash(git diff:*)
---

Current status: !`git status --short`
Changes: !`git diff --stat`

Command composition:

---
description: Full review combining multiple commands
---

/git-status
/file-review README.md

Summarize the above.

Namespacing

Organize commands in subdirectories:

.amplifier/commands/
├── frontend/
│   ├── review.md      # /review (namespace: frontend)
│   └── test.md        # /test (namespace: frontend)
└── backend/
    ├── review.md      # /review (namespace: backend)
    └── deploy.md      # /deploy (namespace: backend)

Commands with the same name in different namespaces are distinguished by their description in /help.

Architecture

Module Structure

amplifier_module_tool_slash_command/
├── __init__.py           # Module entry point
├── tool.py               # Tool implementation (slash_command tool)
├── command_loader.py     # Discovers and loads .md files
├── parser.py             # Parses frontmatter and templates
├── executor.py           # Executes commands with substitution
├── registry.py           # Command registry management
├── template_processor.py # Bash execution, file refs
├── permissions.py        # Granular permission parsing
└── git_fetcher.py        # Lazy fetch/cache for git URL sources

Integration Pattern

This module provides a tool that can be invoked by:

  1. CommandProcessor in amplifier-app-cli (interactive REPL)
  2. AI programmatically via the slash_command tool
  3. Other apps that want extensible commands

Amplifier Protocol Compliance

Implements the standard Amplifier tool protocol:

async def mount(coordinator, config):
    """Register slash_command tool with coordinator."""
    # Returns cleanup function

API

Tool: slash_command

Execute or discover custom slash commands.

Parameters:

  • operation (str): "execute" (default) or "list"
  • command (str): Command name (without leading /) - for execute
  • args (str, optional): Command arguments - for execute

Execute returns:

{
    "prompt": "...",                    # Processed template content
    "bash_commands_executed": 3,        # Number of bash commands run
    "files_included": 2,                # Number of files included
    "warnings": ["..."],                # Any warnings (optional)
    "model_override": "model-name",     # If command specifies model (optional)
    "requires_approval": True,          # If approval needed (optional)
}

List returns:

{
    "commands": [
        {"name": "review", "description": "...", "argument_hint": "..."},
        ...
    ],
    "count": 5,
    "hint": "Use operation='execute' with command='name' to run"
}

Registry Access

The module provides a capability for accessing the command registry:

registry = coordinator.get_capability("slash_command_registry")

# List all commands
commands = registry.list_commands()

# Get command metadata
info = registry.get_command("review")

# Reload commands (useful for development)
registry.reload()

Development

Setup

git clone https://github.com/microsoft/amplifier-module-tool-slash-command
cd amplifier-module-tool-slash-command
uv venv
source .venv/bin/activate
uv pip install -e ".[dev]"

Testing

pytest
pytest --cov=amplifier_module_tool_slash_command

Validation

amplifier-core validate tool .

Roadmap

  • Git URL command sources (shared commands from git repos)
  • MCP prompt integration (expose MCP prompts as commands)
  • Command marketplace (shared command repository)
  • Command versioning (semantic versioning for commands)

License

MIT License - See LICENSE file

Contributing

Note

This project is not currently accepting external contributions, but we're actively working toward opening this up. We value community input and look forward to collaborating in the future. For now, feel free to fork and experiment!

Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit Contributor License Agreements.

When you submit a pull request, a CLA bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

Trademarks

This project may contain trademarks or logos for projects, products, or services. Authorized use of Microsoft trademarks or logos is subject to and must follow Microsoft's Trademark & Brand Guidelines. Use of Microsoft trademarks or logos in modified versions of this project must not cause confusion or imply Microsoft sponsorship. Any use of third-party trademarks or logos are subject to those third-party's policies.