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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely new behavioral context: each figure carries a numerator, denominator and as_of, which tells the agent figures are sourced ratios with a freshness stamp and should be interpreted accordingly. It does not discuss result size or cost when fanning out across all leaves of a parent.

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 dense sentences with zero filler: the primary behavior comes first, the output contents and provenance semantics second. Every clause carries information an agent needs.

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 an output schema present, the description need not detail return structure, and it correctly focuses on mode selection and figure provenance. The one gap relative to a tool with zero required parameters is what happens when neither or both ids are supplied, and whether parent-mode fan-out is bounded.

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 coverage is 100% and the schema already documents both slugs and their origin in list_categories. The description still adds real meaning the schema does not: passing the leaf id yields one brief, passing the parent id yields a brief per leaf, which clarifies the relationship between the two optional parameters. It leaves the both-null / both-set case unaddressed despite required=0.

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 ('Return a structured brief') and immediately distinguishes its two operating modes: a single leaf category vs. one brief per leaf under a parent. The enumerated contents (scale, price distribution, brand concentration, pain points, selling points) make the output concrete. It stops short of naming sibling tools like get_price or get_brand to explain why an agent would pick the aggregate brief over them.

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?

The leaf-vs-parent phrasing implicitly tells the agent how the two parameters select different result shapes, which is useful usage context. However, there is no explicit when-to-use guidance, no statement about when to prefer the sibling tools (get_price, get_brand, get_top100), and no mention of prerequisites beyond the schema's reference to list_categories.

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