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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered and the description adds nothing on top of it. It says nothing about the comparison semantics, what metrics are returned (clicks, impressions, CTR, position?), or whether deltas are computed server-side.

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 front-loaded sentence with zero padding, but at nine words it is under-specification rather than conciseness. The brevity costs information an agent needs rather than saving it.

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 eight parameters, 13% schema coverage, no output schema and no annotations covering semantics, the description carries most of the explanatory burden and discharges almost none of it. An agent would have to infer date formats, the meaning of the current/previous pairing, and the shape of the comparison result.

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 13% – only the dimensions parameter is documented, and that documentation lives in the schema rather than the description. Five required parameters (site_url and the four date bounds) have no stated format, no explanation of the current vs previous pairing, and no note on defaults for row_limit or search_type; the description supplies none of this.

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 pairs a specific verb ("compare") with a resource ("performance") and the notion of two date ranges, which is more than a restatement of the name. However, it never states this is Search Console data, nor does it distinguish the tool from close siblings like get_performance_overview or ga4_compare_periods – only the separate title carries that disambiguation.

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 when-to-use guidance and no mention of alternatives. An agent receives no signal about when to pick this over get_performance_overview (single range) or ga4_compare_periods (GA4 data), or whether the two ranges must be equal length, adjacent, or non-overlapping.

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