Get Sales Rank History

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the agent knows it's a safe read. The description adds that the tool returns a decoded, downsampled time series plus a trend summary, and explains how to interpret rank changes (improving/worsening/stable). This goes beyond the safety profile to set expectations about the response.

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 structured with a purpose statement, a brief explanation of BSR relevance, output summary, argument list, and examples. While longer than necessary, each section adds context and the format is easy to scan.

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?

The description covers the tool's purpose, output structure (time series + trend summary), parameter semantics, and provides two use-case examples. Without an output schema, it could be more explicit about the exact time series format (e.g., array of points), but given the simplicity and the annotations, it's adequately complete.

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?

All three parameters are documented in the schema (100% coverage), so the description's Args section is largely redundant. It does reinforce defaults and adds an example using range='6m', but doesn't provide substantial new meaning beyond the schema descriptions.

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 'Fetch historical sales rank data for an Amazon ASIN from Keepa', which clearly states a specific verb, resource, and scope. It distinguishes itself from siblings like get_price_history and get_best_sellers by focusing on BSR history, further clarified by examples.

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?

The description includes concrete example queries ('Is demand trending up or down...') that signal when to invoke this tool. It doesn't explicitly name alternatives or exclusions, but the examples imply the tool is for demand/BSR history questions, not for price or current best-seller data.

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