R3

Undo your own last change to a project

r3_editor_undo

Destructive

Undo the last change YOU (this agent key or app connection) made to a project: everything one of your tool calls changed is undone together, and the user sees it at once in any R3 tab that has the project open. Use it when your own change was wrong or the user asks you to take it back. It never undoes the user's changes or another agent's: only yours. count undoes your last few changes, newest first.

If someone else changed the same thing after you, that change of yours is SKIPPED: nothing is changed, the answer says who changed what, and that change of yours is dropped from your history (the next call takes the one before it). Their change stands: setting your old value back over theirs is the user's decision, not this tool's.

redo: true puts back what you undid (until you make a new change). Needs project:write (and code:write to undo a change to code).

Input Schema

Name	Required	Description
`redo`	No	true: redo what you undid instead of undoing.
`count`	No	How many of your changes to undo (or redo), newest first (default 1, at most 20).
`projectId`	Yes	The project (r3_project_list).

Output Schema

Name	Required	Description
`left`	Yes
`steps`	Yes
`answer`	Yes	This answer in words: what was done, what R3 measured, decided or refused, and what to do next. The same text as the result's text block. Read it: the fields beside it are the data, this is the guidance.
`headSeq`	Yes
`direction`	Yes
`projectId`	Yes
`skippedSteps`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 15, 2026

addedOutput schema / properties / answer

Added value: +{
+  "description": "This answer in words: what was done, what R3 measured, decided or refused, and what to do next. The same text as the result's text block. Read it: the fields beside it are the data, this is the guidance.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "projectId",
-  "direction",
-  "headSeq",
-  "steps",
-  "skippedSteps",
-  "left"
-]New value: +[
+  "projectId",
+  "direction",
+  "headSeq",
+  "steps",
+  "skippedSteps",
+  "left",
+  "answer"
+]

First observedOct 15, 2026

TDQS

A4.4/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Adds substantial behavior beyond annotations: it explains that all changes from one tool call are undone together, that the user sees the result immediately in open R3 tabs, that conflicting later changes are SKIPPED and dropped from history, and that redo is valid only until a new change is made. It also discloses required permissions (project:write and code:write for code changes), which annotations do not cover.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with the core action and then covers edge cases in a logical order. It is slightly verbose and has some redundancy (e.g., repeating that it only affects the agent's own changes), but every sentence carries useful information for correct invocation.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the complexity of undo/redo with conflict handling, the description covers scope, skip behavior, redo validity, and permission requirements. An output schema exists so return values need not be explained, and annotations already declare the destructive/non-idempotent profile, making the definition complete for an agent to call correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all three parameters in detail. The description repeats 'newest first' for count and adds only the redo window ('until you make a new change') beyond what the schema provides, so it does not meaningfully extend parameter semantics.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Undo the last change ... made to a project') and scopes it precisely to changes made by this agent key or app connection. It distinguishes itself from siblings like release rollback or project changes by explicitly limiting undo to the agent's own tool calls, so an agent can identify it without opening other schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear when-to-use ('when your own change was wrong or the user asks you to take it back') and when-not-to-use ('It never undoes the user's changes or another agent's: only yours'). It does not name an alternative tool for undoing others' changes, so it falls short of the explicit alternatives criterion for a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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