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

Annotations only declare readOnlyHint=false, so the important addition is the description's explicit disclosure that the call is confirm-gated and returns a preview until confirm: true -- a genuine behavioral trait not carried by annotations. It does not say whether omitted images are cleared or left untouched, which matters for a partial-update tool.

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?

Two compact clauses, front-loaded with the action and followed by the gating rule. Nothing is redundant or buried; the prerequisite and the confirm behavior each appear exactly once.

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 mutation with nested branding input and no output schema, the description covers the action, source of inputs, and the preview/execute switch. The only gap is whether a partial update replaces or preserves the unmentioned asset type.

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?

At 50% schema coverage the description carries real weight: it names the two branding targets (logo, square app icon) matching logoKey/iconKey, ties keys back to upload_file, and explains the confirm gate's preview semantics. It stops short of saying the two fields are optional and independent.

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: set the coach's branding logo and/or square app icon from uploaded images. The mapping of 'logo' and 'square app icon' to the two nested fields (logoKey/iconKey) is implicit but recoverable. It never names the closely related sibling update_my_branding, so the agent must infer the split from tool names alone.

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 the key prerequisite -- images must first come from upload_file -- and the confirm condition that governs whether the call previews or executes. It does not state when to prefer this over update_my_branding (other branding fields), leaving that boundary to the sibling's own description.

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