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

Annotations already cover read-only/open-world/idempotent/non-destructive, yet the description adds substantial behavioral context: AI Overview is only read where a paid provider is configured, otherwise a classic organic list of up to 10 results with a note, billing per search with no charge on empty results, and a free SnoopScan key requirement. This is real value beyond the 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-loads the core purpose and packs billing, auth, and fallback behavior into a compact block. Slightly run-on, but nearly every sentence earns its place with no 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?

With an output schema present, return values needn't be described. For a read-only SERP tool, the description covers the auth requirement, billing model, provider-dependent AI Overview behavior, and result-count fallback — everything an agent needs to invoke it 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?

Schema description coverage is 0%, so the description carries the param burden. It clarifies `domain` and gives a format example for `country` ('two-letter code such as gb'), but `depth` and the `aiOverview` boolean toggle are never explained ('up to 10 results' only loosely hints at depth), leaving two of five params undocumented.

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 and resource ('Read a Google results page for a search: who ranks, and what the AI Overview says and cites'), which is a distinct purpose from the generic 'search' sibling. An agent can tell this is a SERP/ranking check rather than a general web search.

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 clear context for use ('Give your domain and the answer says where it ranks and whether the AI Overview cites it') and explains the AI-Overview-vs-organic fallback condition. However, it never names an alternative sibling (e.g. search) or states when NOT to use this tool, so it stops short of explicit routing.

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