---
topic: agentskills-scripts
source_keys:
  - agentskills-using-scripts
---

## One-off commands

When an existing package does what you need, reference it directly in `SKILL.md` without a `scripts/` directory. Use package runners that auto-resolve dependencies:

| Runner | Language | Notes |
|--------|----------|-------|
| `uvx package@version` | Python | Recommended. Ships with `uv`. Caches aggressively. |
| `pipx run 'package==version'` | Python | Mature alternative, broader OS availability. |
| `npx package@version` | Node.js | Ships with npm/Node.js. Pin versions for reproducibility. |
| `bunx package@version` | Node.js | Bun equivalent of npx. Only in Bun environments. |
| `deno run npm:package@version` | TypeScript | Requires permission flags (`--allow-read`, etc.). |
| `go run golang.org/x/...@version` | Go | Built into Go toolchain. |

Tips:
- Always pin versions (e.g., `npx eslint@9.0.0`) for consistent behavior over time.
- State prerequisites in `SKILL.md` (e.g., "Requires Node.js 18+") or in the `compatibility` frontmatter field.
- Move complex commands into `scripts/` when a one-off command is hard to get right on the first try.

## Referencing scripts from SKILL.md

Use **relative paths from the skill directory root**. List available scripts so the agent knows they exist, then instruct it to run them:

```markdown
## Available scripts

- **`scripts/validate.sh`** — Validates configuration files
- **`scripts/process.py`** — Processes input data

## Workflow

1. Run validation:
   ```bash
   bash scripts/validate.sh "$INPUT_FILE"
   ```

2. Process results:
   ```bash
   python3 scripts/process.py --input results.json
   ```
```

The same relative-path convention works in `references/*.md` files.

## Self-contained scripts with inline dependencies

Bundle scripts that declare their own dependencies so the agent can run them with a single command.

**Python (PEP 723 + uv):**
```python
# /// script
# dependencies = [
#   "beautifulsoup4>=4.12,<5",
# ]
# requires-python = ">=3.12"
# ///

from bs4 import BeautifulSoup
# ...
```
```bash
uv run scripts/extract.py
```

**TypeScript (Deno):**
```typescript
#!/usr/bin/env -S deno run
import * as cheerio from "npm:cheerio@1.0.0";
// ...
```
```bash
deno run scripts/extract.ts
```

**TypeScript (Bun):**
```typescript
#!/usr/bin/env bun
import * as cheerio from "cheerio@1.0.0";
// ...
```
```bash
bun run scripts/extract.ts
```

**Ruby (bundler/inline):**
```ruby
require 'bundler/inline'
gemfile do
  source 'https://rubygems.org'
  gem 'nokogiri', '~> 1.16'
end
# ...
```
```bash
ruby scripts/extract.rb
```

## Designing scripts for agentic use

### No interactive prompts (hard requirement)

Agents run in non-interactive shells and cannot respond to TTY prompts. A script that blocks on input hangs indefinitely. Accept all input via command-line flags, environment variables, or stdin:

```
# Bad
$ python scripts/deploy.py
Target environment: _

# Good
$ python scripts/deploy.py
Error: --env is required. Options: development, staging, production.
Usage: python scripts/deploy.py --env staging --tag v1.2.3
```

### Document with `--help`

`--help` output is the primary way an agent learns your script's interface:

```
Usage: scripts/process.py [OPTIONS] INPUT_FILE

Process input data and produce a summary report.

Options:
  --format FORMAT    Output format: json, csv, table (default: json)
  --output FILE      Write output to FILE instead of stdout
  --verbose          Print progress to stderr
```

Keep it concise — it enters the agent's context window.

### Write helpful error messages

```
Error: --format must be one of: json, csv, table.
       Received: "xml"
```

Say what went wrong, what was expected, and what to try.

### Use structured output

Prefer JSON, CSV, or TSV over free-form text. Separate data from diagnostics:
- **stdout** — structured data (JSON, CSV)
- **stderr** — progress messages, warnings, diagnostics

```
# Hard to parse
NAME          STATUS    CREATED
my-service    running   2025-01-15

# Unambiguous
{"name": "my-service", "status": "running", "created": "2025-01-15"}
```

### Further design considerations

- **Idempotency.** Agents may retry. "Create if not exists" is safer than "create and fail on duplicate."
- **Input constraints.** Reject ambiguous input with a clear error. Use enums and closed sets where possible.
- **Dry-run support.** A `--dry-run` flag lets agents preview destructive operations.
- **Meaningful exit codes.** Use distinct codes for different failure types; document them in `--help`.
- **Safe defaults.** Destructive operations should require explicit confirmation flags (`--confirm`, `--force`).
- **Predictable output size.** Many harnesses truncate tool output beyond 10–30K characters. Default to a summary or reasonable limit; support `--offset` for pagination, or require `--output FILE` to opt in to large stdout.