Estimate keyword research cost

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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds useful context by stating it is 'Free' and runs 'without calling a provider', but it does not disclose rate limits, caching, or response structure beyond what annotations already imply.

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?

The description is two short sentences with zero waste, and it is front-loaded with the most important fact ('Free') followed by a precise explanation of what it returns and how it relates to the paid operation.

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?

With six parameters fully documented by the schema, safety hints provided by annotations, and no output schema, the description adequately covers the tool's purpose and return nature ('cost and eligibility'). It could more explicitly tie the estimate to the passed parameters, but the definition is otherwise complete enough for an agent to invoke it correctly.

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 every parameter is already documented in the schema. The description adds no parameter-specific meaning, syntax, or constraints beyond what the schema provides, making the baseline 3 appropriate.

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 states a specific verb ('Returns the cost and eligibility') and resource ('keyword research'), and explicitly distinguishes the tool from its paid sibling by naming 'research_keywords'. An agent can tell exactly what this tool does and what it does not do without opening the schema.

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 clearly positions the tool as the free, no-provider-call estimator and names the paid alternative ('the paid operation is research_keywords'), giving explicit when/when-not guidance. The routing condition between this tool and the paid sibling is unambiguous.

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