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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context not in the annotations: results are compared against a previous period of equal length and a time series is included. It does not cover defaults, limits, or payload size.

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?

A single sentence that front-loads the resource and then enumerates the returned metrics inside a tight parenthetical. Zero filler and no repetition of the tool name.

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 carries the burden of describing the return value, and it does so by listing the metrics, the period-over-period comparison, and the optional series. Default period and series behavior live in the schema, so the description is complete enough for correct invocation, though it could say more about what the comparison output looks like.

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 every parameter (period, from/to, filters, timezone, segment_id, include_series) is already fully documented in the schema. The description adds no parameter-level detail such as date precedence or filter syntax, so the 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 names a specific resource (headline metrics) and enumerates exactly which metrics are returned, plus the period-over-period comparison and time series. An agent can tell it is a summary/overview tool rather than a detailed breakdown, but it never contrasts itself with siblings like get_breakdown, get_pages, or get_realtime.

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?

There is no explicit when-to-use or when-not-to-use guidance and no named alternative. The metric list implies a high-level summary role, but the agent must infer on its own whether to reach for this tool versus get_breakdown, get_pages, or get_realtime.

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