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

Annotations only declare readOnlyHint=false, so the description carries the real burden and does add value: it discloses the confirm-gated preview semantics ('previews until confirm: true'), which is non-obvious behavior for a mutation tool. It stops short of saying what a preview returns or whether omitted branding fields are left untouched or cleared.

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 short parenthetical clauses, all load-bearing: audience scope, capability boundary, and execution gating. No filler and the most decision-relevant fact (Coach Pro only) comes first.

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 nested-object mutation with no output schema and minimal annotations, the description covers scope, the preview/confirm mechanic, and the logo limitation. The remaining gap is update semantics — whether the branding object is a full replace or a merge — which matters given additionalProperties:false and no required sub-fields.

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 50%; the confirm parameter is fully documented in the schema and the pageTemplate enum-ish values and primaryColor pattern are also in the schema. The description adds one genuinely useful constraint — that logo/icon cannot be set here — but says nothing about the branding sub-fields (enabled, displayName) or partial-update 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?

States a specific verb and resource ('Update client-app branding') and immediately bounds the audience ('Coach Pro only; gym coaches use the gym's branding'). It also separates itself from the sibling update_my_branding_images by noting that logo/icon upload happens in the app.

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?

Gives a clear eligibility condition (Coach Pro) and an explicit exclusion with the alternative for gym coaches (the gym's branding). It does not, however, mention calling get_my_branding first to read current values, nor any permission prerequisite beyond the plan tier.

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