history_compare

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds useful context that this reads stored history rather than the live API, but says nothing about retrieval cost, freshness of stored data, or how the two periods are aligned.

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 core purpose and the example are front-loaded in one tight sentence, with no wasted prose. The dangling 'dimension: query, page, country or device' fragment is the only structural weakness, reading like a stray note rather than integrated guidance.

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?

Although an output schema exists (so return values need not be explained), the tool has 8 parameters with no schema descriptions and only one of them partially addressed in prose. For a comparison tool whose correctness depends on correctly pairing start/end with previous_start/previous_end, the definition leaves too much implicit.

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 0% across 8 parameters, so the description carries the full burden and largely fails. It only clarifies that 'dimension' accepts query/page/country/device (values not enumerated in the schema), leaving site_url, start_date, end_date, previous_start, previous_end, limit, and search_type completely uninterpreted.

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 gives a specific verb ('Compare') and resource ('two stored periods') with a concrete example of what a comparison looks like. The phrase 'beyond the API's 16 months' signals this operates on locally stored history rather than live data. It falls short of a 5 because it does not distinguish itself from the sibling 'compare_periods', which an agent could easily confuse it with.

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?

Usage is only implied: the 'beyond the API's 16 months' clause hints that this is the tool for periods the live API cannot cover. There is no explicit when-to-use/when-not statement, and no mention of the competing 'compare_periods' sibling, so the agent must infer the routing decision.

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