get_keyword_rank_history

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

While readOnlyHint=true already signals a safe read, the description goes beyond by detailing default date range, clamping of future dates, swapping of reversed dates, and the PLAN_LIMIT error condition. It also discloses the nested return structure (apps[] with history[]), which is not present in the annotations or schema. This is excellent supplementary transparency.

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 description is information-dense but well-structured: opening purpose, return format, defaults, constraints, error handling, parameter guidance, and an explicit alternative tool. Every sentence contributes value, though it could be tightened slightly by merging some related clauses. At ~120 words, it remains scannable and front-loaded.

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?

For a tool with no output schemacherschema, the description fully covers what to expect in the response (fields like keyword, store, country, lang, resolved dates, apps[] structure). It also covers error handling (PLAN_LIMIT), parameter relationship, and edge cases. Given that the schema already defines the inputs, this is near-comprehensive for a read-only API call.

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?

With 100% schema coverage, the baseline is 3, but the description adds significant meaning: it explains that keyword_id comes from list_keywords, app_id narrows output, and the from/to parameters have default behavior and clamping rules. This goes well beyond the schema descriptions, which only state 'Defaults to 30 days ago' etc., by also defining how invalid inputs are handled.

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 opens with a clear verb-phrase 'Get the daily rank history of one tracked keyword' and immediately distinguishes it from the sibling get_app_score_history by noting the alternative for app-level visibility. The scope ('one tracked keyword', 'one series per app') is precise and differentiates this from other list/inspection tools.

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?

Explicitly states when to use it (daily rank history for a keyword), how to obtain required identifiers ('Pass keyword_id from list_keywords'), and when not to (use get_app_score_history for whole-app visibility). Also documents limits (400-day cap, plan depth) and edge-case handling, giving the agent clear context for invocation.

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