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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds quota behavior not present in structured data: a single call consumes one lookup from the monthly allowance regardless of keyword count, which is a real operational consequence. It does not mention rate limits or what happens when the allowance is exhausted.

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 sentences, both front-loaded with the most decision-relevant information: first the output metric set, then the cost/batching rule. With no output schema, the metric enumeration earns its space by telling the agent what comes back. 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?

Because there is no output schema, the description carries the return-value burden and does so by listing the metrics and history window. Together with annotations and a fully described schema, an agent has enough to call it correctly. Minor gap: behavior when the monthly allowance is exhausted is not stated.

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 100%, so the parameters are already documented with defaults and examples. The description restates the language/location scoping and the 200-cap and adds difficulty units (0 to 100), but contributes little syntax or format detail beyond the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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 (Google search volume for keywords) and enumerates exactly what it returns: monthly searches, 12-month history, CPC, advertiser competition, keyword difficulty, and search intent. The 200-keyword cap and country/language scoping make it distinguishable from sibling keyword tools like keyword_ideas, bing_keywords, and domain_keywords.

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 clear operational guidance: 'One lookup from the plan's monthly keyword allowance whatever the count, so batch keywords into one call.' This tells the agent how to call it cost-effectively. It stops short of naming an alternative tool or stating when this is the wrong choice versus keyword_ideas or domain_keywords.

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