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

With no annotations, the description carries the full burden and delivers the single most important non-obvious trait: this operates on the shared user-visible undo stack, so an undo can clobber concurrent user edits. The expected_revision guidance is genuine safety context beyond the schema. It still omits what happens on a revision mismatch (error vs. silent no-op) and any permission requirements, keeping it out of 5 territory.

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

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

Two sentences, no filler, and the core behavior is front-loaded before the safety caveat. Every clause earns its place.

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

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. For a mutation tool with no annotations, the description covers the shared-stack risk and optimistic concurrency. It leaves out mismatch behavior and permission prerequisites, a modest but real gap.

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

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

Schema description coverage is 0% across 3 params, so the description must compensate. It does explain expected_revision's purpose and implies n is a step count, but 'op' (undo vs. redo, and its default) is never mentioned and n's default of 1 is undocumented in prose.

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

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

Specific verbs (undo/redo) plus the resource and scope ('n steps in the live document'), anchored to a concrete mental model ('the same stack as the user's Cmd+Z'). No sibling tool touches history, and an agent can distinguish this from 'changes' or 'save_copy' immediately.

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

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

Clearly establishes when to reach for it (reverting or reapplying edits in the live document) and gives a concrete condition for passing expected_revision. It stops short of naming when-not or an alternative path, but the sibling list offers no real substitute.

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