What
PostToolUse hooks can now replace tool output for ALL tools (not just MCP tools) via the new updatedToolOutput field.
Details
- Previously, only
updatedMCPToolOutputwas available, which only worked for MCP tools - The new
updatedToolOutputfield works for any tool (Bash, Read, Write, Edit, MCP, etc.) - The old
updatedMCPToolOutputis retained but its description now says "Prefer updatedToolOutput, which works for all tools" - Validation error if hook output doesn't match expected tool output shape: "PostToolUse hook returned updatedToolOutput that does not match {tool}'s output shape"
Evidence
Hook output replacement (search for "updatedToolOutput", "Replaces the tool output before it is sent to the model")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.