Forecast clicks and cost

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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds only the useful detail that results come from Keyword Planner's forecasting; it says nothing about quota consumption, latency of forecast generation, or why the call is open-world.

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 sentence plus a short second sentence, with the metrics and the temporal scope front-loaded. Nothing is redundant and both sentences carry new 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 forecasting tool with a rich, well-annotated 6-parameter schema and no output schema, the description covers what is forecast and over what horizon. It could say more about forecast output shape (ranges vs point estimates) but nothing essential to correct invocation 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 83%, with days, max_cpc, network, language and locations all documented in-schema (including defaults, bounds and geo target ID formats). The description adds no parameter-level meaning beyond that, so the baseline 3 applies.

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 and resource — forecast impressions, clicks, cost, CTR and average CPC for a keyword set over a future period — and names the engine (Keyword Planner). The 'future period' framing implicitly separates it from historical siblings like get_search_volume, but no sibling is named explicitly.

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?

'Useful for budgeting a paid search campaign' gives a loose usage context, but there is no explicit when-to-use/when-not or routing instruction against generate_keyword_ideas or get_search_volume. Guidance is implied rather than stated.

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