Developer explains why read-only AI agent access to spreadsheets is the safer default

A software developer argues that granting AI agents read-only access to spreadsheets is a safer default than the read-write access most tools offer by default. The core concern is that a write-enabled agent can silently corrupt a spreadsheet that serves as a live source of truth, whether through a misfired tool call or a prompt injection attack embedded in a cell. The developer explains that using the Model Context Protocol (MCP) with only read tools exposed means no write path exists at the structural level, making it impossible for an agent to be manipulated into editing data. As an alternative to connecting an entire Google account via OAuth, publishing a single sheet as a standalone read-only endpoint limits the agent's access to only the relevant data. The developer built a tool called PasteSheet around this principle, where read-only is enforced by the server's tool list rather than by rules the agent is expected to follow.