プレーンテキストと書式付き出力の比較

プレーンテキストを使用する場合

プレーンテキストが必要な場合

import anthropic

client = anthropic.Anthropic(api_key='sk-ant-your-key-here')

response = client.messages.create(
    model='claude-opus-4-5',
    max_tokens=200,
    messages=[{
        'role': 'user',
        'content': (
            'Write a 120-character push notification for a flash sale ending in 2 hours. '
            'Plain text only — no emojis, no markdown, no asterisks, no special characters. '
            'Must include: urgency, discount percentage (30%), and category (electronics). '
            'Output the notification text only — nothing else.'
        )
    }]
)
print(response.content[0].text)

プレーンテキストを明示的に求める

import openai

client = openai.OpenAI(api_key='sk-your-key-here')

# Without plain text instruction — likely gets markdown
default_prompt = 'Explain what a webhook is in 100 words.'

# With explicit plain text instruction
plain_prompt = (
    'Explain what a webhook is in 100 words. '
    'Output format: plain text only. No markdown. No asterisks. No headers. '
    'No bullet points. Just continuous prose paragraphs.'
)

for label, prompt in [('DEFAULT (likely markdown)', default_prompt), ('EXPLICIT PLAIN TEXT', plain_prompt)]:
    response = client.chat.completions.create(
        model='gpt-4o', max_tokens=150,
        messages=[{'role': 'user', 'content': prompt}]
    )
    print(f'--- {label} ---')
    print(response.choices[0].message.content)
    print()

メール文面のプレーンテキスト

import anthropic

client = anthropic.Anthropic(api_key='sk-ant-your-key-here')

response = client.messages.create(
    model='claude-opus-4-5',
    max_tokens=300,
    messages=[{
        'role': 'user',
        'content': (
            'Write a 3-paragraph re-engagement email for inactive newsletter subscribers. '
            'Context: SaaS analytics tool, subscriber inactive for 60 days.\n'
            'Format requirements:\n'
            '- Plain text only — no asterisks, no pound signs, no bullet symbols\n'
            '- Paragraph 1: acknowledge absence, create curiosity\n'
            '- Paragraph 2: one new feature they missed\n'
            '- Paragraph 3: CTA with a direct link placeholder [LINK]\n'
            '- No subject line — body only'
        )
    }]
)
print(response.content[0].text)

読みやすい文章の段落

import openai

client = openai.OpenAI(api_key='sk-your-key-here')

prose_prompt = (
    'Explain the advantages of using Docker for development environments. '
    'Write in 3 clean prose paragraphs. '
    'Requirements:\n'
    '- No bullet points or numbered lists\n'
    '- No markdown headers\n'
    '- Use transition words between sentences and paragraphs\n'
    '- Vary sentence length — mix short and long\n'
    '- 150 words total maximum'
)

response = client.chat.completions.create(
    model='gpt-4o',
    messages=[{'role': 'user', 'content': prose_prompt}]
)
print(response.choices[0].message.content)

音声出力用のプレーンテキスト

import anthropic

client = anthropic.Anthropic(api_key='sk-ant-your-key-here')

response = client.messages.create(
    model='claude-opus-4-5',
    max_tokens=200,
    messages=[{
        'role': 'user',
        'content': (
            'Write a 45-second spoken weather briefing for London today. '
            'Conditions: 12 degrees Celsius, light rain, wind 15 km/h from the southwest.\n'
            'Format for voice output:\n'
            '- No markdown symbols of any kind\n'
            '- No parentheses\n'
            '- No abbreviations (write "kilometres per hour" not "km/h")\n'
            '- Natural spoken rhythm — use commas for pause points\n'
            '- Write numbers as words when under ten'
        )
    }]
)
print(response.content[0].text)

既存の出力からMarkdownを削除する

import openai
import re

client = openai.OpenAI(api_key='sk-your-key-here')

markdown_text = (
    '## Key Benefits\n'
    '- **Faster deployment** with Docker containers\n'
    '- **Consistent environments** across dev and prod\n'
    '- Reduced *configuration drift* between machines\n'
    '### Getting Started\n'
    'Run docker-compose up to start all services.'
)

# Option 1: Ask AI to strip
response = client.chat.completions.create(
    model='gpt-4o',
    max_tokens=150,
    messages=[{
        'role': 'user',
        'content': (
            'Remove all markdown formatting from the text below. '
            'Keep all the information but strip: **, ##, ###, -, *, backticks. '
            'Convert bullet lists to flowing sentences. Output plain text only.\n\n'
            + markdown_text
        )
    }]
)
print('AI-stripped:', response.choices[0].message.content.strip())

# Option 2: Simple regex strip (for code-based pipelines)
import re
clean = re.sub(r'[#*]', '', markdown_text).strip()
print('Regex-stripped:', clean)

システムメッセージ内のプレーンテキスト

import anthropic

client = anthropic.Anthropic(api_key='sk-ant-your-key-here')

# System message enforces plain text for all responses
plain_text_system = (
    'You are a helpful assistant embedded in a mobile push notification system. '
    'All your responses are displayed as plain text in mobile notifications. '
    'ALWAYS follow these formatting rules:\n'
    '- Never use markdown (no **, no #, no -, no backtick, no *, no _)\n'
    '- Never use bullet points or numbered lists\n'
    '- Write in 1-2 complete sentences only\n'
    '- Maximum 120 characters per response\n'
    '- No emojis'
)

response = client.messages.create(
    model='claude-opus-4-5',
    max_tokens=64,
    system=plain_text_system,
    messages=[
        {'role': 'user', 'content': 'Notify user their order has shipped and will arrive in 2 days.'}
    ]
)
print(response.content[0].text)

書式を決めるためのフレームワーク

def choose_format(environment, human_reads, code_processes, voice_output):
    '''Simple formatting decision tree.'''
    if voice_output:
        return 'PLAIN TEXT — voice safe, spell out numbers and units'
    if code_processes:
        return 'JSON or CSV — machine-parseable, no prose'
    renders_markdown = environment in ['web', 'notion', 'github', 'vscode', 'obsidian']
    if renders_markdown and human_reads:
        return 'MARKDOWN — headers, bold, code blocks, lists'
    return 'PLAIN TEXT — clean prose paragraphs, no markdown symbols'

scenarios = [
    ('web',         True,  False, False),
    ('email',       True,  False, False),
    ('api_pipeline',False, True,  False),
    ('voice_app',   False, False, True),
    ('terminal',    True,  False, False),
]
for env, human, code, voice in scenarios:
    result = choose_format(env, human, code, voice)
    print(f'{env:<15} -> {result}')

構造化されたプレーンテキスト

import openai

client = openai.OpenAI(api_key='sk-your-key-here')

response = client.chat.completions.create(
    model='gpt-4o',
    messages=[{
        'role': 'user',
        'content': (
            'Write a daily briefing for a developer — 3 sections: TASKS, BLOCKERS, NOTES. '
            'Format: plain text only. '
            'Use ALL CAPS section labels followed by a colon. '
            'Use a line break between sections. '
            'Number each item within a section. '
            'No markdown symbols of any kind. '
            'Use realistic placeholder content.'
        )
    }]
)
print(response.choices[0].message.content)

出力形式の自動判定

import anthropic

client = anthropic.Anthropic(api_key='sk-ant-your-key-here')

def get_format_instruction(channel):
    formats = {
        'web':   'Use markdown formatting: headers, bold, bullet points, code blocks.',
        'email': 'Plain text only. No markdown symbols. Use line breaks between sections.',
        'sms':   'Plain text. Single paragraph. Max 160 characters.',
        'voice': 'Plain text. No symbols. Natural spoken sentences only. Spell out numbers.',
        'api':   'JSON output only. No prose.',
    }
    return formats.get(channel, 'Plain text only.')

def ask_with_channel(question, channel):
    fmt = get_format_instruction(channel)
    response = client.messages.create(
        model='claude-opus-4-5',
        max_tokens=100,
        system=f'Format instruction: {fmt}',
        messages=[{'role': 'user', 'content': question}]
    )
    return response.content[0].text

q = 'What are 3 benefits of regular code reviews?'
for ch in ['web', 'sms', 'voice']:
    print(f'[{ch.upper()}]:')
    print(ask_with_channel(q, ch)[:150])
    print()

理解度チェック

プレーンテキストと書式付き出力 — まとめ