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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false). The description goes beyond them by disclosing that the call surfaces API key permissions and rate limits, which is behavioral context an agent can't infer from annotations alone. It doesn't mention auth requirements or caching, but with annotations carrying safety that gap is minor.

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?

Two sentences, front-loaded with the returned data set followed by a usage directive. The parenthetical quota list is dense but each item earns its place by telling the agent what data is available; only the run-on listing keeps it from a 5.

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, so the description correctly carries the burden of describing return contents (quotas, scan estimate, key permissions, rate limits). Combined with the fully-specified single parameter and safety annotations, an agent has enough to call this correctly; only auth/error behavior is unstated.

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 the single 'brand' parameter is fully documented in the schema (brand id/name/domain, optional for single-brand accounts). The description adds nothing about the parameter, so the baseline of 3 applies.

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 states a specific resource ('plan usage') and enumerates exactly what it contains: quotas used and left for prompts/competitors/articles/manual scans, next scan estimate, API key permissions and rate limits. This is unmistakably distinct from siblings like get_visibility or list_brands, which operate on brands and content rather than account state.

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?

'Call it before planning changes' gives explicit when-to-use guidance. No alternatives are named, but this tool has no overlapping sibling (none of the other 27 tools reports account/plan state), so there is little risk of misselection.

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