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

Annotations already declare readOnly/idempotent/non-destructive, yet the description still adds non-obvious behavior: results come 'newest first', reflect a 'daily read', enumerate exactly which attributes are tracked, and handle the empty case. Most valuably it discloses a side-effect boundary — 'Reading this does not mark anything as seen' — which no annotation conveys.

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 dense sentence with the change scope front-loaded before the tracked fields and the empty-state caveat. The opening 'For a business that tracks competitor apps in GrowthDept' is mild framing overhead but does establish context, and no clause is truly redundant.

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 parameters and no output schema, the description carries the return burden itself and does so: it lists the attributes compared (title, description, screenshots, icon, version, price, category, rating), the ordering, and the no-change outcome. An agent could call this and interpret the result without further information.

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 nothing for the description to disambiguate beyond what the schema already shows. Baseline 4 applies for a no-argument tool.

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 and change-framing: 'what each one changed on its App Store or Google Play listing, newest first', which implicitly separates it from a static listing tool like app_store_listing. It never names a sibling explicitly, so the differentiation is inferable rather than stated.

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?

It scopes the audience ('For a business that tracks competitor apps in GrowthDept') and notes 'Says when nothing has changed', which implies the tool is for change-monitoring rather than current-state lookup. There is no explicit when-not guidance and no named alternative such as app_store_listing or check_app_stores.

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