Brand ad summary

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

readOnlyHint=true already tells the agent this is a safe, non-mutating read, so the description does not need to restate safety. It adds the useful fact that the result is aggregated (counts, format breakdown, duration) rather than a raw listing, but says nothing about scope, time window, or result size.

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?

A single 15-word sentence with the core action front-loaded and the colon-delimited payload spelled out immediately after. No filler and nothing repeated from the title.

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 no output schema and no parameters, the description is the only source of truth, and it covers the return shape reasonably well. It leaves open which brand is summarized and what reporting window or scope the stats cover, which is a real gap for a zero-argument tool.

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?

The tool takes zero parameters, so there is no parameter semantics for the description to compensate for; baseline 4 applies. The description correctly does not invent or describe nonexistent inputs.

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?

Specific verb and resource ('Get a summary of a brand's advertising') plus the concrete contents of that summary (ad count, formats, run duration), so an agent knows exactly what comes back. It stops short of 5 because it never distinguishes itself from siblings like get_brand_ads or compare_brands, and does not clarify whose brand (the zero-parameter schema implies the caller's own brand, but the description says 'a brand's').

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?

No when-to-use guidance, no exclusions, and no mention of the closely related siblings (get_brand_ads for individual ads, compare_brands for cross-brand comparison). The agent must infer the placement from the name alone.

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