google_ads_generate_keyword_forecast_metrics

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

With no annotations, the description carries the disclosure burden and does well: 'read-only planless RPC does not create a campaign or saved plan' plus 'temporary keyword campaign' clearly signals no persistent side effects. It does not cover auth or rate-limit behavior, but the key mutability trait is transparently disclosed.

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?

Two dense sentences with no filler: the first leads with the action and output metrics, the second summarizes supported features and the side-effect disclaimer. The structure front-loads the most decision-relevant 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 complex 18-parameter tool with no annotations and no output schema, the description covers the core purpose, returned metrics, supported options, and side-effect profile. It still lacks explicit guidance on choosing this versus sibling forecast/idea tools and on return-value shape, but the schema fills most parameter detail.

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 56%, so the schema already documents many parameters. The description adds value by grouping capabilities ('targeting, negatives, match type, three bidding strategies, explicit future dates, and an optional independent per-keyword breakdown'), but it does not explain individual parameter semantics or required combinations, modestly supplementing the schema.

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 and resource: 'Forecast impressions, clicks, CTR, CPC, cost, conversions, and CPA for a temporary keyword campaign.' It lists the exact output metrics and the scope. The 'forecast' framing distinguishes it from historical/idea siblings, and the direct statement that it 'does not create a campaign or saved plan' further separates it from creation-style tools.

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 clear context: use this tool for forecasting a temporary keyword campaign, and it explicitly states what it does not do ('does not create a campaign or saved plan'). However, it never names an alternative such as google_ads_generate_keyword_historical_metrics for past-performance needs, so the when-not/alternative guidance is not fully explicit.

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