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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds modest context about what the card contains (data categories and purposes), but says nothing about auth needs, caching, or rate limits, and the return shape is already captured by the output schema.

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, both front-loaded and purposeful: the first defines scope, the second is a compact disambiguation list. Zero filler.

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?

Complete for a read-only single-app lookup: purpose, scope, sibling routing, annotations and a full output schema are all present. An agent needs nothing more to select and call it correctly.

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%, so ID, Country and Lang are fully documented in the schema. The description adds no format, syntax, or default information beyond that, making the baseline 3 appropriate.

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 ('Fetch') and resource ('App Store privacy cards for an app') plus the payload contents ('data categories and purposes'). It is clearly distinguishable from appstore_app, appstore_ratings and cross-store siblings without opening any schema.

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?

Explicitly routes the agent: names four alternatives (appstore_app, appstore_ratings, googleplay_datasafety, chromewebstore_privacy) and the condition that selects each (app details, aggregate reviews, Android data-safety label, extension privacy label). Nothing is left to inference.

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