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

Annotations already declare readOnly, idempotent and non-destructive behavior, so safety is covered. The description adds that the result is a complete snapshot rather than a single pair, but says nothing about which currencies are included, how missing dates behave, or the data source.

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?

One short, front-loaded sentence with no filler. The trade-off is that terseness leaves the sibling differentiation and result shape unstated.

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 one-parameter read-only lookup with annotations and a fully described schema, this is close to sufficient, but 'full snapshot' is undefined (all currencies? cross rates?) and no guidance on missing or default dates appears beyond the schema default note.

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% and the single date parameter is fully documented including the default, so the description cannot add much. It confirms the date selects a snapshot rather than a range, but supplies no format or edge-case detail beyond the schema.

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?

States the specific resource (exchange-rate snapshot) and scope ('full', USD base) with a date qualifier. The explicit '(USD base)' implicitly separates it from get_rates_by_base, but the distinction is left to inference rather than stated.

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?

Usage is only implied: the USD-base note hints that other bases belong to a sibling tool, but the description never says when to call this versus get_rates_by_base, get_history, or convert. No prerequisites or exclusions are given.

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