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

Annotations already disclose readOnlyHint=false, destructiveHint=true and idempotentHint=true; the description earns credit for explaining WHY it is destructive — 'keywords (a new list replaces the old)' — instead of contradicting the hint. It also adds non-schema behavior: unchanged fields are preserved and changes apply only to future drafts, which is genuinely useful. It does not cover permissions or whether the edit is reversible, so it stops short of full disclosure.

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?

It is short and front-loaded with the mutable field list, then the patch semantics, then the downstream consequence and the alternative tool. The middle clause 'Future drafts use them' is pronoun-heavy and slightly opaque out of context but carries real information, and no sentence is filler.

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?

With an output schema, full parameter coverage and complete annotations, the description only needs to add mutation semantics and routing, which it does. For a 5-parameter mutation tool flagged destructive, the main residual gap is the absence of any permission/prerequisite or reversibility note.

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 100%, so the parameters are already documented, and much of the field list is duplication of the schema. The description still adds meaning the schema does not: all fields other than brand_id are effectively optional and omitted keys are left untouched, plus the whole-list replacement semantics for `keywords` are surfaced in the prose rather than discovered by the agent in the schema alone.

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?

The description opens with a specific verb plus resource ('Edit a brand') and enumerates the four mutable fields (name, voice, target_market, keywords), so an agent knows exactly what the tool touches. It also draws one sibling boundary by naming `redraft_video_direction` for the adjacent drafting task, but does not distinguish itself from `create_brand` or `update_product` beyond the implicit 'edit vs create' wording.

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?

It states the patch contract clearly: 'only the fields you pass change', which tells the agent it may send a minimal payload, and it explicitly redirects to `redraft_video_direction` for rewriting an already-drafted direction. It stops short of naming when NOT to edit a brand (e.g. brand creation, or that new values do not retroactively affect existing drafts), leaving that to inference.

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