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

With no annotations, the description carries the full disclosure burden and meets it: cross-month snapshot deduplication, one-result-per-plan representation, response-local plan_sequence without standalone IDs, has_more pagination rather than exact totals, and contains/exclusive semantics are all stated explicitly. This goes well beyond the structured schema.

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 dense, front-loaded sentences cover purpose, data model, matcher semantics, pagination, and the key alternative. Every sentence contributes information, and there is no filler or repetition of schema content.

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 filtered read tool with no output schema and no annotations, it covers result identity, matcher behavior, pagination, and the totals alternative. It does not fully describe the response envelope or date/range constraints, but the schema handles most parameter mechanics and the tool remains safely invocable.

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 applies. The description mostly re-expresses country_match semantics that the schema already documents, and adds general plan-identity context rather than per-parameter details. It neither compensates for missing schema info nor introduces ambiguity.

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 opens with a specific verb-resource pair ('Discover a game's ad plans') and names the filter dimensions: countries, platforms, format, dates. It also distinguishes itself from material/ad tools by noting results have no standalone ad/creative IDs, and from get_game_platform_stats by directing totals there.

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 provides an explicit routing hint: 'Use get_game_platform_stats for totals.' It also clarifies contains vs exclusive country matching, which tells the agent how to choose match behavior. It does not enumerate all non-use cases, but the data-model caveats give sufficient selection context.

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