Mistral Vibe: write_file Now Create-Only
Mistral VibeMistral Vibe v2.14.0 introduced a breaking change to the write_file tool: it is now create-only and will refuse to overwrite any file that already exists. Previously, write_file could both create new files and overwrite existing ones in a single operation. Agents that relied on write_file to update existing files will now need to use the search_replace or edit tool instead. This change reduces the risk of agents silently destroying file content during automated runs.
write_file is Now Create-Only
Starting with v2.14.0, Mistral Vibe's write_file tool operates in create-only mode: it will create a new file successfully, but will refuse to overwrite a file that already exists on disk.
What Changed
Previously, write_file behaved as an upsert operation, writing the full file content regardless of whether the target path already existed. The new behavior is strict: if the target file is present, write_file will return an error rather than overwriting it.
To modify an existing file, agents must now use the search_replace or edit tool, which operate on diffs and make targeted changes rather than replacing the entire file content.
Why This Matters
The change addresses a class of data-loss scenarios where an agent with write_file access could inadvertently overwrite a file it did not intend to replace. In automated or long-running agent sessions, this kind of silent overwrite could destroy carefully crafted content or revert manual edits. By splitting creation from modification into two distinct tools, Mistral Vibe makes the agent's intent explicit and auditable at each step.
Impact on Existing Workflows
Any agent prompt, skill, or AGENTS.md instruction that relies on write_file to update an existing file will now receive an error at runtime. Users should audit their workflows and replace write_file calls on existing paths with edit or search_replace calls. New file creation remains unaffected.
This is a deliberate safety trade-off: slightly more friction for update operations in exchange for a significant reduction in accidental file destruction risk.