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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: the data comes from official broker fee tables, each record carries the source URL and a last-confirmed date, promotions are scoped to today, and results are facts without ranking or recommendation.

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?

Content scope is front-loaded in a single dense sentence and the trust caveats (source URL, confirmation date, no ranking) land at the end where they belong. The comma-separated enumeration is heavier than ideal but every item carries selection 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?

An output schema exists, so return-value details need not be explained, and the description covers source provenance, freshness, and the no-recommendation stance. What is missing is any guidance on combining the two filters or on behavior when the broker name does not match.

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 both the broker filter and the market enum are fully documented in the schema. The description mentions GPW, US and German markets, which loosely mirrors the market enum, but adds no syntax, default behavior, or semantics for the optional broker filter. 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?

Opens with a specific verb+resource: "Fees of brokers available to Polish investors from their official fee tables," and enumerates the fee types covered. It is clearly separable from siblings like get_bank_rates and get_currency_rates, though it never names a sibling or explicitly contrasts itself with them.

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?

Usage is implied by the enumerated content (online commissions, account fees, IKE/IKZE, promotions valid today), so an agent can infer when this tool fits. But there is no explicit when-to-use statement, no exclusion, and no pointer to an alternative tool for related data.

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