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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered structurally. The description adds that the result is coverage/date-range information, which is genuine behavioral context. It says nothing about auth requirements, latency, or whether coverage is per-property granularity beyond the term 'per-site', so it stays at an adequate-plus level.

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?

Two sentences, roughly fifteen words, with purpose first and the call-ordering instruction second. Nothing is redundant and nothing important is buried.

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?

This is a simple, annotation-covered, read-only tool with an output schema, so return values need not be spelled out. Purpose plus call ordering is what an agent needs here. It loses a point only because 'per-site' versus the parameter's all-properties default is not reconciled in prose.

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% and the single site_url parameter already documents the 'if provided / if None' branch, so the schema does the work. The description's 'per-site' wording only loosely signals that site_url scopes the result; it adds no format or semantics beyond the schema. Baseline 3 applies.

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 the resource and scope concretely ('Per-site archive coverage') and immediately ties it to a sibling tool, so an agent knows this reports available archive date ranges rather than querying them. It stops just short of a full verb+object phrasing like 'Get archive coverage per site', but the meaning is unambiguous.

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 gives explicit sequencing guidance — 'Use this before search_analytics_archive' — which names both the alternative and the condition that selects it. There is no statement of when *not* to use it, but for a one-parameter preflight tool the positive guidance is essentially complete.

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