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a11y_undo_edit

Revert an applied edit from the current session by restoring its backup; if no edit ID is given, undo the last edit. Removes files created by that edit.

Instructions

Undo an applied edit from this session by restoring the backup (the last one if edit_id is empty). An edit that created a file is undone by removing that file.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "a11y_undo_edit"
  }
}

Input Schema

Name	Required	Description	Default
`edit_id`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.1.0Oct 19, 2026

TDQS

A3.7/5.0

Behavior4/5

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

With no annotations, the description carries the full burden and does well: it discloses the restore-backup mechanism, the special case where a file-creating edit is undone by deleting the file, and the default-to-last-edit behavior. It omits error/failure behavior (bad or out-of-session edit_id) and whether the undo itself is reversible.

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?

Two tight sentences with the core action front-loaded and the fallback/edge-case behavior second. No filler, though the second sentence could be folded in more tightly.

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

Completeness4/5

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

An output schema exists so return values need not be described, and the one parameter's key behavior is covered. The remaining gap is failure handling and the destructive side of removing a created file, which matters for a mutation tool with no annotations.

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 coverage is 0% — edit_id has no description at all — so the description's note that an empty edit_id undoes the last edit is genuinely valuable. It does not explain the format of edit_id or where the agent obtains it, so it only partially compensates for the coverage gap.

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

Purpose4/5

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

The description names a specific verb and resource ('Undo an applied edit') and even the mechanism ('restoring the backup'), so it is clearly the inverse of the sibling a11y_edit_file. It stops short of explicitly naming or contrasting with any sibling tool, which is what a 5 requires.

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

Usage Guidelines3/5

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

Usage is strongly implied by the name and the 'from this session' scoping note, which does rule out undoing edits from prior sessions. However, it never states when to use this versus alternatives (e.g., a11y_approve_edit) or any preconditions, leaving the agent to infer.

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