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

The description adds substantial behavior beyond the annotations: each call spends one monthly quota unit, including authenticated failures, and is never retried. It also discloses the Enterprise plan requirement and a preflight response-size constraint, which explains the non-read-only and non-idempotent hints.

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 dense and front-loaded with the quota cost, then gives the core purpose, plan requirement, size constraint, and endpoint. Every sentence carries operational value.

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 four-parameter tool with no output schema, the description is complete enough: it explains output granularity as one entry per date, gives the critical quota and plan constraints, and specifies the preflight size limit.

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%, so the schema already documents the four parameters. The description adds meaningful cross-parameter semantics: the date span must be at most 365 days, and days multiplied by currencies must not exceed 2000, including the default-currency implication of 174 currencies per day.

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: daily exchange rates for every date from start_date to end_date. It also defines the granularity and date range, which clearly separates it from live-rate, conversion, historical, and rate-change siblings.

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 clear usage context and constraints: Enterprise plan required, maximum 365-day span, and response-size limits checked before the request. It does not explicitly name when to use a sibling instead, so it falls short of full alternative routing.

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