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

The annotations already mark the operation as non-read-only and potentially destructive; the description adds valuable behavior beyond them: synchronous behavior, response envelope behavior, rejection semantics (HTTP 200 still used), measured payload sizes, and billing cost. It does not fully explain what destructive side effect exists, but it also does not contradict the annotations.

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 dense but efficiently organized: purpose first, then size, depth choice, cost, and error-envelope behavior. The return-field list is slightly redundant with the output schema, but each other sentence earns its place.

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 billed live endpoint, the description covers response location, error behavior, cost, depth choice, and approximate response size. The main gap is request-body guidance, but the schema supplies that structure, so the description is otherwise sufficient.

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?

With schema description coverage at 0%, the description does not compensate for the input contract: it mentions `keyword` only among returned fields and never explains that the caller must send a `body` array containing keyword/location identifiers. The agent must still reverse-engineer request shape from the schema alone.

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 first sentence states a specific operation: return advertisers matching a query in Google's ads transparency data, and it emphasizes the synchronous execution. This clearly differentiates the tool from organic-search and Google Ads search siblings by naming the resource type ('advertisers'). No inference is needed to understand what the tool does.

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?

The description gives explicit selection guidance among the three result depths, positioning `advanced` as the default and saying when to use `regular or `html`. It does not name sibling tools like `gads_search_live` as exclusions, but the depth-selection rule is clear and actionable.

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