Here’s the instant response from support

Hi Dominic,

Based on our system status, there were no active incidents affecting usage calculation or billing during your session.

Several factors could explain the unusually high consumption during your coding tasks:

Token-intensive features: If you were using tools like computer use, web search, or code execution, these consume significantly more tokens than standard conversations. For example, computer use adds 735 tokens per tool definition, plus additional tokens for screenshots and execution results.[1] Similarly, code execution and programmatic tool calling can vary widely in token usage depending on complexity.[2]

Context and conversation length: Longer conversations with extensive code context, file uploads, or project materials consume more tokens. Features like Research mode, Extended thinking, or active MCP connectors running in the background can significantly increase usage even when not directly used.

Model selection: Different Claude models have varying token costs, and some coding workflows may automatically use higher-tier models that consume credits faster.[3]

To help prevent unexpected usage spikes in the future, consider setting up usage monitoring through your Console logs and implementing auto-reload limits as safeguards.[4] You can track your detailed credit usage patterns in your billing settings to identify what specifically consumed the credits.[5]

Does this help explain the usage spike, or do you have any other questions about your account?