Get commodity price fluctuation

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

With no annotations, the description must carry the transparency burden. It discloses the output fields (start rate, end rate, absolute change, percent change) and implies a read-only operation via 'Returns'. However, it does not mention important behaviors such as silent omission of invalid symbols, which is only covered in the schema parameter description, not in the tool description itself.

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 a single sentence that is front-loaded with the core action and lists the specific output fields. Every word earns its place; there is no fluff or repetition.

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 query tool with no output schema, the description sufficiently explains the return values and inputs. The schema covers the key edge case (invalid symbols omitted). The only minor gap is not mentioning date format or any limitations, but these are either in the schema or low-risk for a read-only fluctuation query.

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 description coverage is 67% (symbols and startDate have descriptions; endDate refs startDate). The tool description adds minimal parameter context ('one or more commodity symbols', 'start and end date') but does not compensate for the 33% gap with format details. The schema already provides the example and invalid-symbol behavior, so the description adds marginal value.

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 ('Returns') and identifies the resource ('commodity symbols') and the precise computation ('changed between a start and end date: start rate, end rate, absolute change, and percent change'). This clearly distinguishes it from sibling tools like get_latest_rates or get_time_series.

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 implies the use case (calculating price changes over a period) but does not explicitly state when to choose this tool over siblings or provide exclusions. It lacks references to alternatives like get_historical_rates for raw history or get_latest_rates for current prices.

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