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

Annotations already declare idempotentHint=true, destructiveHint=true, and openWorldHint=false. The description adds non-obvious behavior beyond them: updating reuses the existing primary market and does not consume an extra-market add-on. It does not, however, explain what happens to the prior location value or why destructiveHint is set, leaving a small gap.

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?

Front-loads the verb and effect, then usage, then a billing note, then arg docs. Well-structured, though the quota sentence and the formatted Args block make it slightly longer than strictly necessary.

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?

No output schema exists, and the description supplies purpose, triggers, the quota nuance, and four of five parameters. It stays silent on overwrite semantics for an existing location and any permission requirements, which for a destructive-marked mutation is a minor missing piece.

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 only 20%, so the description must compensate, and it does for most params: brand_id (required, the brand to update), country (ISO-2 with 'UK' alias and full-name acceptance), region, and city with narrowing semantics. The fifth parameter, user_intent, is not mentioned at all.

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 a brand's primary location') and immediately explains the effect: pinning the home market so competitor/AI analysis is measured against the right region. It is clearly distinguishable from siblings like list_brands and manage_competitor.

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 explicit triggers: use it when list_brands shows a brand has no location, or when its competitor set looks geographically wrong (with a concrete example of a UK-only brand compared against US companies). Both the when and the routing signal (list_brands) are named.

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