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

Beyond the readOnly/openWorld annotations, it discloses real operational facts: the App Store Connect key needs the Admin role, Apple publishes the first report a day or two after connecting, and the subscription output only appears when a vendor number is saved. That is genuine behavioral context; it stops short of saying anything about pagination or result volume.

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?

One ~130-word run-on sentence that packs downloads, subscriptions, and product-page metrics into a single breath. The main purpose is front-loaded, but the remainder is dense and hard to parse, and metric definitions like startRate and pageRate are buried mid-stream.

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 does a good job enumerating what comes back (downloads by source/country/campaign, trial and conversion events, visibility/view/Get counts), which offsets the missing return schema. However, the two input parameters and the conditional nature of the subscription payload remain underspecified.

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 0% for both parameters. The description only obliquely implies the 'days' window ('for the last days') and says nothing about the 1–35 bound or what 'appId' expects, so it fails to compensate for the empty schema documentation.

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 names a specific resource (first-time downloads and redownloads) and enumerates the dimensions returned: source, country, campaign, subscription events, and product-page funnel metrics. It is clear what the tool produces, though it never names a sibling (e.g. analytics, app_countries) to differentiate scope.

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?

Usage is only implied: 'With the vendor number saved, also what came after the download' hints at a prerequisite for the subscription section, but there is no explicit when-to-use / when-not-to-use statement and no alternative tool is named despite many siblings covering adjacent analytics data.

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