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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds two traits not in annotations: data is cached hourly (freshness/staleness expectations) and the service is free (no cost gating). It stops short of noting whether a stale cached value can be forced to refresh.

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 tight line with the resource and quote direction front-loaded, plus the useful cached-hourly parenthetical. The trailing 'Free.' fragment is terse to the point of being cryptic, and 'etc' leaves the supported currency set unspecified.

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?

With no output schema, the description should say what comes back (a code-to-rate mapping, ordering, or partial-result behavior), and it does not. It covers freshness and cost but leaves the response shape ambiguous for a tool with no output schema to fall back on.

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 single `codes` parameter is fully documented in the schema including the ISO 4217 format and the omit-for-all default. The description adds nothing about the parameter beyond reinforcing USD/EUR as examples, 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 specific resource (KZT exchange rates) and clarifies the quote direction — KZT per unit of USD/EUR — which is a real semantic detail, not a restatement of the name. It never names or distinguishes itself from the sibling fx_rates, so an agent must infer that this is the KZT-scoped variant.

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?

There is no when-to-use guidance at all, and notably no statement about when to pick this over the sibling fx_rates. The 'omit for all' default lives in the schema, not the description, so routing relies entirely on the tool name.

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