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

Annotations declare the safety profile (destructiveHint=true, idempotentHint=true), and the description adds genuinely non-derivable behavior: only the keys present in the patch change, the kit's source is forced to 'manual' and sourceUrl is preserved, and the call fails for a brand with no existing kit unless the patch is complete. That is exactly the mutation-side-effect detail an agent needs.

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 dense sentences: what it updates is front-loaded, then patch semantics, then the failure condition. No filler and nothing redundant with the name/title.

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-patch mutation tool with annotations but no output schema, the description covers field scope, partial-update behavior, side effects on source/sourceUrl, and the failure precondition. Only brandId's role and identity goes unexplained.

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 0%, so the schema names the patch keys but explains none of them; the description compensates by enumerating and grouping them (colors including primary/accent/background/foreground/palette, fonts fontFamily/headingFont, logoUrl, voiceDescription). The brandId parameter is left entirely unexplained, which is the only real 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?

States a specific verb ('Update') and resource ('brand's visual identity kit') and enumerates the exact surface it touches: colors, fonts, logoUrl, voiceDescription. An agent can immediately distinguish it from get_brand_kit, create_brand_kit_upload and update_brand_profile.

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?

Provides meaningful application context (partial-patch semantics, and the failure case when no kit exists unless every required field is supplied), but never names an alternative or says when to reach for update_brand_profile vs create_brand_kit_upload vs this tool. Usage is implied rather than routed.

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