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

Annotations already declare read-only, idempotent, open-world, and non-destructive behavior, so the bar is lower. The description adds useful context beyond annotations: the ranking order ("most overvalued first"), the raw vs GDP-adjusted distinction, the allowed base currencies, and the data source/license.

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 front-loaded with the core operation and scope, then gives a concise use case and source attribution. Every sentence is short and 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 read-only data-ranking tool with full schema coverage and safety annotations, the description is nearly complete. It explains the operation, ordering, base currency options, and adjustment type, though it does not detail the returned columns in the absence of an output schema.

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 100%, so the schema already documents all four parameters including date format, limit, adjusted, and base_currency enum. The description repeats base currency options and raw/adjusted but adds no new syntax or format meaning beyond the schema, making the baseline 3 appropriate.

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 verb and resource: rank every currency in a Big Mac index release by over/under-valuation against a base currency. It includes scope details (base currency options, raw vs GDP-adjusted, most overvalued first), which clearly distinguishes it from a generic index lookup such as big_mac_index.

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?

It gives an explicit use case: "Use for 'which currencies are cheapest/most expensive by the Big Mac index'." However, it does not name alternatives, exclusions, or when not to use this tool versus big_mac_index, so it falls short of full routing guidance.

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