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

Annotations already declare readOnly/idempotent/non-destructive/open-world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: a hard GSC connection prerequisite, an actionable setup URL, and the multi-account resolution rule (property read through the account that can see it).

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?

Four sentences, front-loaded with purpose and value before prerequisites. Most sentences earn their place; the multi-account clause is slightly tangential but still actionable.

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 read-only breakdown tool with no output schema, the description covers purpose, value, and setup/auth context adequately. Return shape and the rowLimit default are left to the schema, which is acceptable.

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 100% and all four parameters are documented in the schema, so baseline 3 applies. The description adds no syntax or format detail beyond that, though none is really needed.

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 ('Get search traffic broken down by country') with explicit dimension (country), which an agent can immediately distinguish from sibling breakdown tools such as get_gsc_device_breakdown or get_gsc_top_queries.

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 context for when the tool is valuable ('understanding geographic audience and international SEO performance') and states the prerequisite wiring. It stops short of explicitly naming alternative siblings or exclusions, which keeps it below a 5.

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