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

Annotations already declare the mutation profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), so safety is covered. The description adds the partial-update contract in "only pass what should change", which is genuine behavioral context not in the annotations, but says nothing about scope of effect (account-wide vs. page), reversibility, or whether omitted fields reset.

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 with the primary purpose front-loaded and the partial-update rule stated early. The parenthetical restating the `style` enum values duplicates schema content, which is minor waste but the passage stays short overall.

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, zero-required, nested-object configuration tool with no output schema, the description covers purpose and update semantics but leaves the bulk of the parameter surface undocumented. An agent would be guessing at most fields from bare enum names.

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% and the description explains just 2 of 14 parameters (style, preset), including the useful style-to-preset dependency. With twelve parameters, a nested background object, and no required fields, the description fails to compensate for the coverage gap.

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?

Names a specific verb (Change) and its resources (colours, fonts, layout and other theme settings), so the agent knows exactly what domain this covers. It does not differentiate itself from set_profile, the nearest sibling, which also mutates user-level configuration.

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" is a real usage instruction for partial updates and is useful. However, there is no when-to-use vs. alternative guidance, no prerequisites, and no statement of when this tool is inappropriate relative to siblings like set_profile.

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