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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuinely new behavior: the data is official, published daily (freshness expectation), and free (no key or quota). It stops short of saying what happens with an unrecognized ISO code or how the response is shaped.

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?

A single front-loaded sentence: resource, source, quoting basis, then cadence and cost. The trailing 'Free.' fragment earns its place by preempting an auth question, and nothing is redundant.

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-optional-parameter read tool with full annotation coverage and a fully documented schema, this is nearly sufficient; source authority, cadence and cost are all present. The only shortfall is the absence of any return-shape hint, which matters slightly since no output schema exists.

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% and the single optional codes parameter is fully documented there, including the omit-for-all behavior and an example. The description only gestures at the same idea with 'USD/EUR/etc', adding nothing new, so the 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), the authoritative source (National Bank of Kazakhstan), and the quoting convention (per unit of USD/EUR), so an agent knows exactly what it gets. It does not distinguish itself from the sibling fx_rates tool, leaving the agent to guess which rate source to pick.

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 or when-not guidance and no mention of the sibling fx_rates, which is the obvious alternative for exchange-rate queries. The only implicit signal is that this is the official NBK source, which hints at authoritative-rate use cases but never states it.

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