get_google_ads_impression_share

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

With no annotations provided, the description must carry the full behavioral burden. It explains the meaning of metrics and gives interpretation heuristics, but does not disclose important operational details such as required permissions, rate limits, or what happens if no client_id is provided when multiple clients exist. For a read-only metrics tool, this is a notable gap.

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, followed by metric explanations and decision rules. It is efficient and each sentence adds value, though the transition from 'estimated_missed_impressions shows the scale...' to the decision rules could be slightly tighter. No redundant 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?

For a 6-parameter, no-required-parameter tool with no output schema and no annotations, the description covers purpose, metrics, and actionable thresholds well. However, it omits behavioral aspects like authentication/configuration requirements and result format, which are needed for safe invocation. It is adequate but not fully complete.

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 the schema already documents all parameters in detail. The description adds no parameter-specific information (e.g., format, default behavior) beyond what the schema provides. Thus, baseline 3 is 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 opens with a specific verb (Retrieves) and resource (impression share metrics), and explicitly scopes it to Search and Performance Max campaigns. It clearly distinguishes itself from the sibling performance tools by focusing on impression share, loss breakdown, and opportunity metrics.

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 provides actionable interpretation rules (budget-lost > 20% → increase budget; rank-lost > 30% → improve bids/QS) and directs to list_clients for client IDs, which gives clear context for when to use the tool. However, it does not explicitly state when to use this tool versus other performance tools or any exclusions.

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