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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well beyond them: it says the answer is indicative only with nothing exchanged, that commission is none, and that the response carries the rate used, the applicable side, hours/limits notes and special-rate eligibility. That is substantive behavior an agent cannot infer from the annotations.

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?

Purpose and the user-voice examples are front-loaded, and the closing "Indicative only: nothing is exchanged" is a well-placed caveat. The middle enumeration of return fields (hours, limits, commission, timing, special rate, ruble terms) is a long run-on list that could be tightened.

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?

There is no output schema, so the description must describe what comes back — and it does, covering the converted result, rate used, side, and ancillary notes. Combined with the readOnly annotations and full schema coverage, an agent has everything needed to call this correctly.

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 amount, from, to and both enums (channel, language). The description only reinforces amount/from/to indirectly through its examples and adds nothing about channel defaulting or language selection, so baseline 3 applies.

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 concrete verb and outcome — converting an amount at FXHUB's live rate — and the two quoted example queries make the resource unambiguous. It is clearly a calculator rather than a rate-list, but it never names the sibling get_exchange_rates, so a sibling distinction is only implied by the examples.

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 two quoted user questions ("How much is 1,000 USD in GEL?", "How many euros for 5,000 GEL?") give concrete trigger conditions, which is strong context for when to call. It stops short of exclusions or naming alternatives, so an agent gets a positive trigger but no rule for preferring this over get_exchange_rates.

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