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

Annotations already declare readOnly (safe read) and openWorld, so the bar is lower. The description adds valuable non-obvious behavior: limit is billed in pages of ~10 and rounded up, so requesting 11 yields two pages — this billing/quota behavior is not in the schema or 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?

Front-loaded with the core purpose and return shape, then params, then use cases. Dense but every sentence carries information; the field enumeration is long yet useful given no output schema.

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?

With no output schema, the description usefully enumerates the returned record structure (organicResults, paidResults, relatedQueries, peopleAlsoAsk, metadata). Safety profile is covered by annotations. Complete enough to invoke correctly; could mention rate limits or result freshness.

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 coverage is 100%, so the baseline is 3. The description nonetheless adds meaning by clarifying the rounding/billing semantics of limit beyond the schema's own note, and confirms the required body shape {query, limit}.

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+resource (Google Search results, SERP) for a query, returned as JSON, and enumerates the exact fields returned. An agent can distinguish it from siblings like web-search or google-news without opening the schema.

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?

Gives concrete use cases — rank checks, source discovery, grounding answers — which implies when to invoke it versus generic web-search. It does not explicitly state when NOT to use it or name the closest alternative (web-search), so it stops short of a 5.

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