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

Annotations already declare this as a safe, idempotent, non-destructive read, so the bar is lower; the description adds real value beyond that with corpus freshness ('refreshed daily'), coverage breadth ('thousands'), and 'No API key required'. It does not discuss rate limits or result caps, which the limit/offset params imply but the prose leaves silent.

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?

Three tight sentences: scope first, filter axes second, returns/requirements last. Every clause carries information and there is no filler or restatement of 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?

For an 8-parameter search tool with no output schema, the description covers the corpus definition, filter dimensions, the shape of the return value ('slugs'), and the follow-up tools that consume it. Nothing an agent needs to invoke it correctly is missing.

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 88%, so the schema already documents nearly every parameter, including enum meanings for chart and platform. The description restates the same filter categories (text, tag, genre slug, chart rank, has_video) without adding syntax, defaults, or interaction rules (e.g., chart requires category), so baseline 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?

States a specific verb and resource ('Search ... App Store listings') plus the exact scope of the corpus (top 100 free and top-grossing per Apple category, refreshed daily). This clearly separates it from siblings like list_directory_categories, list_directory_tags and get_directory_app.

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 description enumerates the five filter axes (text, genre slug, tag, chart rank, preview video) and names the downstream tools whose slugs it returns (get_directory_app, get_app_videos, get_app_history, create_restyle), which tells an agent where this fits in a workflow. It does not state when to prefer a sibling list tool instead, so it stops short of full when/when-not guidance.

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