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

Annotations already establish read-only, idempotent, open-world behavior, so the bar is low; the description nonetheless adds that results come from the store's own similar-apps list and are compared on rating, price, installs (Android only) and last update. The Android-only qualifier on installs is a genuinely useful caveat.

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 tight sentences, with the core action and the store-source qualifier front-loaded before the example queries. Nothing is redundant or 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?

With no output schema, the description compensates by indicating what the comparison is based on (rating, price, installs, last update), which hints at returned fields. It does not describe ordering or what happens when no similar apps exist, a minor gap for a simple two-parameter read tool.

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 both parameters are already documented, including the app_id format examples and the limit range, so the schema does the heavy lifting. The description adds no further meaning about app_id format or limit behavior, matching the baseline 3.

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 apps similar to a given app") and pins down the data source as "the store's similar-apps list," which separates it from a generic search. It stops short of naming the sibling search_apps/get_app, so sibling discrimination is implicit rather than explicit.

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 examples "apps like X" and "alternatives to X" give a clear trigger context for invocation. There is no explicit when-not guidance or named alternative (e.g., search_apps for keyword discovery), so it falls short of a 5.

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