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

With readOnlyHint=true already conveying safety, the description adds valuable behavioral details: the after-window is clamped to now, route-level pageviews appear when the annotation recorded routes, and a note may be returned indicating truncated or missing data. It also instructs the agent to relay the note and qualify percentages, which is transparent about response semantics.

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 compact, with each sentence earning its place: the core function, the window behavior, the routing detail, the timing caveat, and the note-handling instruction. It is front-loaded with the primary purpose and contains no filler or repetition.

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?

Given the output schema exists and the annotations cover safety, the description covers everything an agent needs: what is measured, how the window works, special-case behavior, and how to handle caveats in the response. Nothing important is left unstated for correct invocation and interpretation.

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 adds meaning beyond the schema by explaining window_days as 'N days preceding vs following' and highlighting the after-window clamping behavior. This enriches the agent's understanding of the parameter's practical effect without being redundant with the schema.

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 ('compare') and resource ('recorded annotation') with the exact metric ('visitors and pageviews in the N days preceding vs following it'). It clearly distinguishes from sibling tools that address other analytical questions or site management, making it unambiguous what this tool is for.

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 gives clear context for when to use the tool (after an annotation has been recorded) and includes explicit guidance to 'wait a few days after shipping.' It does not name alternative tools or state when not to use it, but the annotation-specific framing makes the usage context strong enough for an agent to select it appropriately.

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