Site overview

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context beyond the annotations: the period comparison against the prior period, the fact that totals match the Search Console UI, and the data-lag note in the days parameter. It doesn't describe pagination or exact response shape, but for a read-only overview tool this is sufficient.

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 two sentences with zero filler. The most important guidance ('first tool to call') is front-loaded, followed by concrete output details and a clear pointer to the alternative. Every sentence earns its place.

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 read-only overview tool with two well-documented parameters, no output schema, and strong annotations, the description covers the essential context: what it returns, how the period comparison works, when to use it, and when to use the sibling instead. Nothing an agent needs to invoke it correctly is missing.

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 both parameters well. The description adds value by explaining the comparison semantics ('against the period before') and the data-lag context ('ending about 3 days ago because Google data lags'), which go beyond the schema's parameter descriptions. It doesn't add much about the site parameter, but the schema already covers accepted formats and the list_sites hint.

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 states a specific verb ('call first'), a clear resource ('how a site is doing on Google'), and enumerates the exact outputs (totals, deltas, top pages, plain-language actions). It also distinguishes itself from the sibling search_performance, so an agent can tell them apart without opening schemas.

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 explicitly says 'The first tool to call for any question about how a site is doing on Google' and names the alternative for custom breakdowns ('use search_performance instead'). This gives both a positive trigger and an exclusion condition, which is exactly the when-to-use guidance an agent needs.

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