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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false, openWorldHint), but the description adds real behavioral context: the counterfactual design against the whole site to strip seasonality and Google updates, the plan requirement (Starter and up), and the underlying GSC Search Analytics API it reads. It doesn't discuss rate limits or latency, hence a 4 rather than 5.

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?

Front-loaded with the core question and the comparison method, with the plan/read-only/API details trailing. Slightly redundant, since 'Did a change work?' repeats the title and opening line, and the raw API URL is verbose, but every sentence carries information.

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?

No output schema exists, yet the description tells the agent what comes back (a before/after table and a plain verdict), plus the data source and plan gate. Combined with fully covered parameters, an agent has nearly everything needed; only edge-case behavior (e.g., insufficient data) is unaddressed.

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 all four parameters are already documented in the schema, and baseline is 3. The description contributes one extra insight — that specifying a url judges a single page against the whole site — but adds no format or unit detail beyond what the schema provides.

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?

States a specific verb and resource — compares the weeks after a marked change with the same number of weeks before — and frames the whole tool as answering 'did my change work?'. An agent can distinguish this measurement tool from siblings like track_change (which marks the change) without opening the schema.

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?

Gives clear context for when to use it (after a marked change, or any date) and notes that the change date can be omitted to fall back to the most recent marked change. It does not explicitly name an alternative tool or state exclusions, so it stops short of a 5.

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