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

With no annotations, the description carries the behavioral burden and does well by disclosing the underlying data window (90 days), the nature of the operation (judging a price, not modifying anything), and the specific outputs (verdict, percentile, median, all-time low, sample size). It does not mention error cases or data availability limits, but the core behavior is transparent.

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 concise sentences, with the core answer front-loaded. The second sentence prevents misuse by excluding flight search, and the third explains the unique data requirement. No repetition or filler; every sentence contributes useful context.

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 two-parameter tool with no output schema, the description effectively covers the return values and the tool's non-search nature. It does not elaborate on edge cases or how the percentile should be interpreted, but the essentials—how to call, what to expect, and when it applies—are present. Sibling differentiation could be stronger, but it is adequate.

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?

Schema coverage is 100%, with both origin and destination thoroughly described including format constraints and examples. The description adds no new parameter-level detail beyond calling it a 'route,' so the baseline score 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 states a specific purpose: answering 'buy now or wait?' for a route based on 90 days of price history. It clearly distinguishes itself from flight search by saying 'This is not a flight search: it judges a price.' This separates it from any search-like siblings and defines the tool's resource as price verdicts.

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 phrase 'buy now or wait?' clearly signals when to use the tool: when deciding whether to purchase a fare for a known route. It explicitly excludes flight search scenarios, but does not name or contrast the sibling tools cheapest_months and when_to_book, so alternative selection is left somewhat implied.

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