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

Annotations already declare destructiveHint=true, so the description's job is to say what is destroyed: it specifies that sections revert to their prior state, scoping the blast radius. It also names a concrete failure mode (JEV_UNDO_CONFLICT) and its trigger condition, which is real added value beyond the annotations. It stops short of saying whether the undo itself is reversible or whether all sections of an entry are affected.

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 dense sentences with zero waste: effect first, failure condition second. Nothing is repeated from the schema or annotations.

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?

For a two-parameter mutation with full schema coverage, no output schema, and annotations covering the safety profile, the description supplies the essential missing pieces: revert semantics and the conflict error. Only the reversibility of the undo and per-section vs whole-entry scope remain unstated.

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 100%, so both title_id and entry_id are already documented, including the provenance of entry_id. The description adds only a general sense of what an entry represents, which is baseline-appropriate when the schema does the heavy lifting.

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?

States a specific verb (undo) and a precisely scoped resource (one entry of the Title's config history), and enumerates the entry kinds it covers (tuning, agent, creation change). An agent can tell this apart from tuning_apply and list_tuning_history, though those siblings are not named explicitly.

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?

Usage is implied by the narrow purpose plus the conflict rule, and the schema points at where entry_id comes from (tuning_apply or list_tuning_history). There is no explicit 'use this when...' routing or statement of when not to undo (e.g., after a newer change), leaving the agent to infer it.

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