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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds that the output is a join of SQP rows with ads coverage evidence, which is useful, but it does not explain what a 'coverage_state' means, how data gaps surface, or the freshness behavior that include_diagnostics hints at.

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?

A single front-loaded sentence with no filler; the core resource and the join are stated immediately. It is perhaps too terse to count as ideal structure for a 15-parameter analytical tool, but nothing is wasted.

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?

An output schema exists, so return-value enumeration is not required. However, for a complex joined analytics tool with 15 params and a domain-specific coverage_state enum, the description omits the conceptual model (what a coverage row represents, what 'no_paid_coverage_observed' vs 'data_gap' imply), leaving the agent to infer usage from schema alone.

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% across all 15 parameters, including the three enums and pagination, so baseline is 3. The description adds no parameter-level detail beyond the schema (e.g., what min_volume interacts with, or how date range defaults to a 30-day SQP week window).

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?

States a specific verb ('Returns') and resource ('SQP search query rows joined to observed ads search-term and keyword-target coverage'), which distinguishes it from get_search_query_performance and get_search_terms. It is precise but heavy with domain jargon (SQP, coverage) that an agent must already understand, so it stops short of 5.

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 says nothing about when to choose this tool over get_search_query_performance or get_search_terms, nor about prerequisites or when the join is meaningful. With ~90 sibling tools, the absence of routing guidance is a real gap.

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