Cross-app audience overlap

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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real behavioral context beyond them: a store id yields an empty 200 that still costs a request, and name resolution costs one extra request per 100 results. These cost/failure semantics are valuable and non-obvious.

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 tight sentences: purpose first, then the critical id constraint, then the name-resolution cost note. No filler and every sentence carries actionable 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 read-only tool with no output schema, the description covers the input gotcha (unified id), a failure mode, and the cost of name resolution. Pagination and return-shape details are not addressed, which keeps it just under fully complete.

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 80%, near the high baseline of 3. The description goes further than the schema on two params: it specifies app_id must be a 24-hex unified id (not a store id) and explains that resolve_names triggers additional per-100-results requests, meaning the description adds value the schema does not carry.

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+resource: 'Which other apps this app's users also use.' An agent immediately understands this is cross-app audience overlap. It does not explicitly differentiate from the nearby sibling sensortower_audience_affinity, so it stops short of a 5.

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 a concrete prerequisite (get the unified id from sensortower_app_metadata) and a hard usage rule (24-hex unified_app_id ONLY). It does not name a when-not condition or an explicit alternative for overlap-style questions, but the routing to the metadata tool is a clear usage cue.

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