currency_rates

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

Annotations already declare readOnly/idempotent/non-destructive/open-world, so the safety profile is covered. The description adds useful auth context ('no key') and hints that rates are everyday rather than central-bank official, but says nothing about rate freshness, update cadence, or currency coverage.

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?

Two tight sentences, the core capability and default are front-loaded, and every clause carries information (default, no key, sibling relationship). No filler.

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 tool with an output schema and full annotations, this is close to sufficient. The remaining gap is ambiguity around what 'everyday' rates mean (source, freshness, currency set), which an agent would want before trusting results.

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 parameter already documents ISO 4217 codes, case-insensitivity, and the AED default. The description only restates the default, adding nothing beyond the schema; baseline 3 is 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?

States a specific resource (exchange rates) and its scoping unit (a base currency, defaulting to AED). The closing reference to the 'official cbuae central-bank rate tools' signals it is a distinct, non-official counterpart, though it never explicitly says how the two differ in data source.

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?

'Everyday' rates versus 'official cbuae' rates implies a usage distinction but never spells out when to pick this tool over cbuae_exchange_rates, cbuae_base_rate, or currency_convert (which converts amounts rather than listing rates). The agent must infer the choice from adjectives alone.

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