google_ads_auction_insights_get

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

With no annotations, the description fully carries the transparency burden. It explicitly states 'Read-only', details the exact return format (single-entry list with fields and None/percentage values), describes failure responses with specific error keys, and discloses the API version limitation on competitor-level data.

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 front-loaded with the core purpose, then proceeds through return format, error format, read-only note, API limitation, and alternative tool. Every sentence adds substantively distinct information; there is no redundancy or fluff.

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?

Given no output schema, the description fully covers return values and error handling. It also explains the data limitation and points to a sibling tool. Combined with the well-documented input schema, the description provides a complete picture for an agent to use this tool 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?

Input schema covers 100% of parameters with descriptions, so baseline is 3. The description does not add additional parameter-level details beyond the schema, but the schema itself is rich (e.g., period guidance, customer_id fallback) and the description's mention of returned fields provides helpful output context.

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 uses a specific verb ('Fetch') and resource ('raw impression-share metrics for one Google Ads campaign'), clearly distinguishing it from sibling google_ads_auction_insights_analyze by calling it 'raw' and explicitly pointing to the analyze tool for human-readable insights.

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?

Explicitly names the alternative tool ('For a version with human-readable insights layered on top use google_ads_auction_insights_analyze') and explains the API v23 limitation, helping agents decide when raw impression-share proxies are sufficient versus when to use the richer analysis tool.

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