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

Annotations already mark this as read-only and non-destructive. The description adds meaningful behavior context: quantity-weighted averaging, min/max per base unit, merchant inclusion, bucket comparison, and the insufficient-history fallback. No contradiction with annotations.

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 three sentences with the core purpose front-loaded)Skip. Every sentence adds distinct value: the behavior summary, the example question, and the output-handling instruction. There is no filler or duplication of schema content.

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?

With no output schema, the description carries the burden of explaining return semantics, and it does so well: average/min/max per base unit, merchants, bucket comparisons, and the few-buckets fallback. Combined with complete schema parameter notes, an agent has enough to call and interpret the tool correctly.

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 covers all six parameters with descriptions, so the baseline is 3. The description repeats the month/week default and gives a product example, but does not materially clarify date, merchant, or householdId semantics beyond what the schema already states.

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 clearly states what the tool does: it shows how a product's unit price moved over time from receipt photos, with aggregation details. It specifies the resource (product price history) and distinguishes it from sibling receipt/search tools even without naming them.

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 gives a concrete question the tool answers ('how much has the price of apples gone up this year') and explains the bucket comparison behaviorhare. It does not explicitly contrast it with alternatives like search_receipt_items or summarize_receipt_items, so it falls short of full exclusion guidance.

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