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

Annotations declare the write/safety profile, and the description adds genuinely non-obvious behavior: existing cell values are not altered, an edit permission is required, and supplying an id replaces rather than appends. That last point is important given idempotentHint=false. It does not address what happens if the range already carries a non-checkbox validation.

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?

Purpose is front-loaded, then the definition parenthetical, then create-vs-replace, then the permission and value caveats, ending with a compact signature. Every clause carries information, but the parenthetical and the trailing signature make it dense enough to read as a run-on.

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, and the description covers permission, value preservation, and id semantics. What remains unaddressed is conflict behavior with pre-existing validations of another type on the same range — a plausible edge case for a four-parameter mutation.

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 coverage is 75% with file_uuid undocumented in the schema, and the signature line plus inline prose covers all four parameters including which are optional. The id parameter's replace-vs-create semantics and range's checkbox meaning are explained beyond the schema text, though file_uuid still gets no real meaning from either source.

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 uses a specific verb and resource ('Adds checkboxes to a range') and then clarifies the underlying mechanic — a boolean data-validation rendered as a checkbox with TRUE/FALSE cell values. That definition implicitly separates it from the other validation setters (files_set_dropdown, files_set_number_validation, files_set_custom_validation) without the agent needing to compare schemas.

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 clearly states the create-vs-replace decision rule ('Pass id (from files_validations) to replace that rule; omit to create') and names the sibling tool that supplies those ids. It also states the edit-permission prerequisite. It stops short of saying when to prefer a different validation type instead, so exclusions are missing.

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