App metadata

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

Annotations only cover readOnlyHint and openWorldHint, so the description carries the interesting behavioral burden and does so exceptionally: it discloses that the endpoint does NOT validate the API key (garbage token still returns 200) and that an unknown id returns an empty list rather than an error. These silent-failure warnings are exactly the kind of non-obvious behavior an agent needs.

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, front-loaded with the high-value detail (the unified_app_id) and then the two traps. Every clause earns its place with no filler.

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 an 8-parameter metadata tool with no output schema, the description covers the returned fields, batching behavior, and the critical edge cases (silent auth and missing-id failures), while annotations and the 100%-covered schema handle the rest. Nothing needed to call it correctly is missing.

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 100%, so the baseline is 3 and the schema already documents os/id mixing traps, fields, format, and dry_run. The description adds only the batching limit (100 ids), which the schema's app_ids text also states, so it contributes little beyond structured data.

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 enumerates exactly what the tool returns (name, publisher, categories, rating, version, unified_app_id), making it clearly the app-metadata lookup. The verb is implicit (a field list rather than 'Fetch metadata for...'), but the resource and scope are unambiguous and it differentiates itself from sibling endpoints by being the source of the unified_app_id.

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 signals a cross-tool dependency by noting the unified_app_id is 'critically' required by every unified endpoint (overlap, audience insights), which hints at when to call this first. However, it never states when to prefer this over siblings like app_estimates or app_rank, and gives no explicit exclusions.

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