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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value the annotations cannot: cost ('Free'), output scope ('delivers no reviews'), and the behavioral effect of default country on Google Play review language selection.

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 short sentences, front-loaded with the core action, then routing, then the cost/scope caveat. Every clause carries distinct information and nothing is padded.

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?

An output schema exists, so return-value detail in the description is a bonus rather than a requirement, and the annotations cover safety. Combined with the routing cues and the cost note, an agent has everything needed to call this correctly and to place it in the workflow.

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 the baseline is 4 and there is nothing for the description to disambiguate. The mention of 'default country' concerns returned data rather than an input, so it neither helps nor hurts parameter understanding.

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 ('List the apps this Rivioo user saved') and enumerates the returned fields (store, app_id, default country), so the agent knows exactly what this yields. It also implicitly separates itself from rivioo_find_app by framing the scope as the user's saved list rather than a lookup, and names the downstream tools it feeds.

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?

Gives clear when-to-use context: 'look up an app the user names before calling rivioo_review_stats, rivioo_search_reviews or rivioo_get_reviews.' The clause 'Free; delivers no reviews' acts as a when-not for review retrieval. It never explicitly contrasts with rivioo_find_app, which is the closest alternative, so it stops short of full routing guidance.

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