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

With no annotations, the description carries the full burden and does meaningful work: it discloses the required auth level (Admin role), a data-availability latency (first report one to two days after connecting), and cost (free). It stops short of describing return structure, pagination, or behavior when no data exists.

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 front-loaded sentence delivers the metric, breakdowns, and source, with compact parentheticals explaining the source taxonomy and the sf-* campaign meaning. No filler; every clause adds information.

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?

For a simple two-parameter read tool with no output schema, the description covers what is produced, how it is broken down, and the operational conditions for success. It is nearly complete, lacking only a note on return shape and the appId parameter's role.

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%, so the description must compensate. It clarifies that 'days' means the recent window ('for the last days'), but says nothing about 'appId' or that 'days' is capped at 35. Partial compensation for two undocumented parameters.

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 metric (first-time downloads and redownloads), the breakdown dimensions (source and campaign), and the data source (App Store Connect analytics reports). It is unambiguous about what the tool returns, though it does not name a sibling tool to distinguish itself from close relatives like 'analytics'.

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 gives availability context (Admin-role key required, first report lands a day or two after connecting, free), which helps an agent know prerequisites. However, it never states when to prefer this over alternatives such as 'analytics', and provides no explicit exclusions, so usage is only implied.

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