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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is clear. The description adds context about data availability ('when records are available') and the output nature ('Shows price trends over time'), which goes beyond the annotations. However, it lacks details on return format or pagination, which would make it richer. With annotations covering safety, this is an adequate but not exceptional contribution.

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 two short sentences, front-loaded with the primary verb and resource. Every phrase earns its place: the period limit, data availability caveat, and the output trend hint. No fluff or repetition of schema details.

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 read-only tool with low complexity (3 params, no output schema), the description covers the core purpose, constraints, and availability caveat. It doesn't mention the optional retailerId filter, but the schema already documents that. The output type ('price trends') is implicit but not fully specified, which is acceptable given the tool's simplicity.

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?

The input schema has 100% parameter coverage with clear descriptions for all three parameters (days, productId, retailerId). The description reinforces the 'days' limit (up to 365 days) but does not add new semantic meaning beyond the schema, so the baseline of 3 applies.

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 uses a specific verb ('Get') and resource ('price history') with a clear scope: a product over a period up to 365 days. It clearly conveys that the tool returns historical price data, showing price trends. However, it does not explicitly distinguish itself from the sibling cf_price_summary, so it misses the top score.

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 provides no guidance on when to use this tool versus alternatives like cf_price_summary or other product/offer tools. It does not mention any exclusions or preferred scenarios, leaving the agent to infer usage from the tool name and context. This is a significant gap for tool selection.

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