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

Annotations already declare destructiveHint=true and readOnlyHint=false, but the description adds important behavioral detail: classes and fees move over, the folded subject is removed, and the operation requires owner-level access. It could say more about reversibility or confirmation, but it meaningfully supplements the annotations.

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?

The definition is a single dense sentence with the main action front-loaded and the permission constraint at the end. The parenthetical detail is useful and there is no filler, though the sentence is somewhat compressed and could be easier to parse if structured more explicitly.

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 destructive mutation with no output schema, the description covers the key effects: what moves, what is removed, and who can perform it. It does not explain reversibility, conflicts, or return behavior, but that is a minor gap given the annotations and full schema coverage.

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 the schema already explains both parameters. The description reinforces that `into` is a list of 1 to 5 subject ids to keep and that `id` is folded away, but this largely restates structured information rather than adding substantial new semantics.

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?

The description states a specific verb and resource: folding one subject into another or splitting a combined subject into several. It distinguishes merge versus split behavior and names the fields affected. The phrase 'two spellings' is slightly ambiguous, but the core purpose is clear.

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?

It implies when to use the tool via merge or split scenarios and adds an 'Owner only' permission note. However, it does not explicitly contrast with related siblings such as save_subject, remove_subject, or merge_levels, nor does it state when not to use this instead of those alternatives.

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