Price history

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

With no annotations, the description carries the behavioral disclosure burden. It reveals that results are sorted newest last, that each observation includes price, currency, source, and confidence, and that free accounts see only the last 30 records. This is meaningful behavioral context beyond the schema, though it does not address errors or the id/url selection behavior.

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 sentences with no filler. The primary action and target resource are front-loaded, and the behavioral details are concise and relevant. Every sentence earns its place.

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 simple list operation with three optional parameters and no output schema, the description adequately covers return fields, ordering, and a service limitation. It lacks explicit guidance on conflicts between id and url or error cases, but those are minor for this 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 already covers all three parameters with descriptions, so the baseline is 3. The description adds useful semantics by framing id/url as identifying a single watch and by linking the free-tier 30-record cap to the limit parameter. This goes slightly beyond the schema's basic property 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 states a specific action ('list stored observations') on a specific resource ('one watch') and details the returned data: price, currency, source, and extraction confidence. This clearly distinguishes it from siblings like price_check, which would focus on current pricing rather than historical observations.

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 explicitly instructs when to use the tool ('Call this tool to list stored observations for one watch') and gives context about ordering and free-tier limits. It does not explicitly name alternative tools or exclusion conditions, but the use case is clear enough to route an agent correctly.

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