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

Beyond the readOnlyHint annotation, the description discloses important behaviors: the tool is scoped to the active Space by default, can return the whole Space if unscoped with a risk of overflowing the response budget, and supports per-call Space override via space_id. This adds meaningful context not derivable from annotations alone.

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 sentences, front-loaded with the core purpose, and every clause contributes meaning (scoping recommendation, space behavior, override option). No redundant or filler content.

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 list tool with no output schema, it explains scoping, Space behavior, and potential overflow. It does not explicitly state the return structure (e.g., list of keyword objects with cursor), but this is somewhat covered by cursor schema referencing meta.nextCursor. Overall adequate for the complexity.

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?

The schema already provides 100% parameter descriptions, so the baseline is 3. The description adds value by explaining the 'server-side' scoping mechanism and the practical consequence of not using ad_group_id/campaign_id (overflow risk), which goes beyond the schema's individual field descriptions.

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 clearly states the tool 'List keywords across visible campaigns' with a specific verb and resource. It distinguishes itself from sibling tools like get_keyword or list_ads by naming the resource and mentioning scoping by ad_group_id/campaign_id.

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 provides clear usage context: recommends passing ad_group_id or campaign_id to scope results server-side and warns that omitting them may overflow the response budget. It also explains how to switch Space via set_active_space or override per call with space_id, but it does not explicitly contrast with alternatives like get_keyword.

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