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

Annotations already declare non-read-only, idempotent, non-destructive, closed-world, so safety is covered. The description adds genuinely useful behavior beyond that: it is a partial/patch update where omitted fields are untouched. It still says nothing about the scope of the change (account-wide vs. page-level) or permission requirements.

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?

Three tight sentences, front-loaded with the action and the partial-update rule before the parameter notes. The parenthetical re-listing of style options mildly duplicates the schema enum, but it usefully anchors the cozy=Desk mapping.

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 14-parameter tool with a nested background object, no output schema and 7% schema coverage, the description is far too thin. It never explains how style/preset interact with the individual knobs (does preset override accent?), what the other twelve parameters do, or whether changes are global or scoped.

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 only 7% (just `style`), so the description must carry the load for 14 parameters and it explains only two of them (`style` and `preset`). Font, align, accent, avatar, effect, layout, motion, photos, radius, ambient, tileStyle and the entire nested `background` object are left as bare enum values with no meaning attached.

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 concrete verb ('Change') plus the resource and its parts (colours, fonts, layout, other theme settings), so an agent knows exactly what this does. It does not explicitly contrast itself with the nearest sibling set_profile, which is the only gap keeping it from a 5.

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?

'Only pass what should change' gives the key partial-update usage rule, and it routes the agent to list_options to discover which palettes pair with which look. There is no explicit when-not-to-use guidance (e.g. versus set_profile or per-tile styling in update_tile).

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