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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is known. The description adds two pieces of context not in the structured data: the tool is free (no credits), and passing null clears a field — the latter explains how destruction actually occurs. It stops short of warning that clearing is irreversible.

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 sentences, zero waste, with the core update semantics front-loaded before the cost note.

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 an 11-parameter mutation with 9% schema coverage and no output schema, the description covers the essential calling pattern (partial fields, null clearing) but omits validation constraints and does not note that the response/effect is limited to the passed fields. Adequate but with clear gaps.

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 9% — only brandId is documented. The description compensates for the biggest semantic gap by explaining partial-update and null-to-clear behavior across the ten nullable fields, but it says nothing about the value constraints baked into the schema (description minLength 30, 10-item caps, the language enum), leaving those to be inferred from raw schema.

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+resource: 'Update fields on an existing brand.' The word 'existing' implicitly separates it from create_brand and delete_brand without naming them, so an agent can route correctly, but there is no explicit sibling differentiation.

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 clear operational guidance for a partial-update tool: pass only fields that change, and pass null on a nullable field to clear it. It does not state when to prefer this over alternatives (e.g. create_brand), but the update-vs-create distinction is inherent in 'existing brand'.

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