AI API Key, Model & Character Limit Settings

Write Buddy works by registering just one API key from OpenAI, Anthropic (Claude), or Google. The AI service being used is automatically detected from the format of the API key you enter, so in most cases setup is complete once you paste in a single key. All settings are configured on the “Settings” → “Write Buddy” page in the WordPress admin screen.

Official API Key Documentation for Each AI Service

Choose one AI service to use and obtain an API key from the official site below (you do not need to register with all three providers).

• OpenAI (GPT): https://platform.openai.com/api-keys
• Anthropic (Claude): https://console.anthropic.com/settings/keys
• Google (Gemini): https://aistudio.google.com/apikey

For each service, issuing an API key requires creating an account and registering a payment method (for usage-based billing). Follow the instructions on each provider’s site for detailed steps. Note that if you use an Anthropic (Claude) API key, automatic featured image generation will not be available (because Anthropic does not offer an image generation API). If you also want to use the image generation feature, use an OpenAI or Google API key instead.

How to Register Your API Key

1. In the left-hand menu of the WordPress admin screen, open “Settings” → “Write Buddy”.
2. Paste the API key you obtained directly into the “API Key” field.
3. Click “Save Changes” at the bottom of the page.
4. After saving, if a notice reading “Current setting: recognized as XX” appears at the top of the screen, the AI service has been correctly auto-detected.

If Auto-Detection Doesn’t Work (Manually Specifying the Provider)

If the AI service cannot be automatically detected from the format of the API key, a warning reading “Saved, but the AI service could not be recognized” will appear. In this case, use the “Manual Provider Override” field to directly select the service you are actually using.

• Auto-detect (default)
• Anthropic (Claude)
• OpenAI (GPT)
• Google (Gemini)

Normally, leaving this set to “Auto-detect” is fine. Manual selection is only needed if the automatic detection is incorrect.

Deleting Your API Key

If an API key is already registered, a “Delete the saved API key” checkbox will appear. Check this box and save to delete the registered key.

How to Register the Model to Use

In the model settings fields on the “Settings” → “Write Buddy” page, you can enter the name of the AI model you want to use directly (this is a text field, not a dropdown). If left blank, the recommended model for the detected AI service will be used automatically.

• Image Generation Model: Enter the name of the model to use for generating featured images.
• Text Model for Proofreading & Chat: Enter the name of the model to use for proofreading, AI chat, the quick article generator, and considering the composition of featured images.

The default models used when the field is left blank (as of the time this guide was written) are as follows. The available model names may change depending on the plan and availability on the AI service’s side.

• Anthropic (Claude): Text model claude-haiku-4-5 (no image generation model available)
• OpenAI (GPT): Text model gpt-5-mini / Image generation model gpt-image-1-mini
• Google (Gemini): Text model gemini-2.5-flash / Image generation model gemini-2.5-flash-image

If you want to use a specific model (for example, a higher-accuracy, higher-tier model), enter the model name provided by the respective AI service into the field and click “Save Changes.”

How to Set the Character Limit

Below the model settings fields, the “Maximum Characters Sent for Proofreading” field lets you set the maximum number of characters of post content sent to the AI.

• Default: 6,000 characters
• Minimum allowed value: 500 characters (adjustable in increments of 100 characters)

This limit applies not only to “Proofread Content” but also to the post content sent to AI chat and the post summary the AI references when considering the composition for featured image generation. Any content beyond the limit is automatically truncated before being sent.

Note that the reference URLs and reference files loaded by the quick article generator feature are subject to a separate, fixed limit (a maximum of 8,000 characters per reference item, 20,000 characters in total, and up to 5 reference URLs), which cannot be changed.

After changing the settings, click “Save Changes” at the bottom of the page to save them.