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

With no annotations, the description carries the full behavioral burden and does so well: it discloses the Polish business-day publishing calendar, the weekend/holiday fallback to the most recent preceding publication, the presence of effectiveDate to reveal the date actually used, and the 2002-01-02 data start. These are exactly the non-obvious traits that would otherwise cause wrong assumptions about dates.

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 front-loaded single paragraph with no filler — purpose first, then the calendar/fallback caveat, then the data-range bound. It is dense enough that splitting into purpose-and-behavior sentences would scan faster, but every clause carries information.

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?

All three optional parameters are covered and the return payload is partially characterized via effectiveDate, which matters because there is no output schema. It stops short of describing the shape of the rate list itself (currency code plus mid/bid/ask fields), which is the only remaining gap for a caller.

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 schema already documents date, table, and no_cache, making 3 the baseline. The description earns above baseline by adding real semantics for `date`: the business-day fallback rule and the historical lower bound (2002-01-02) are not derivable from the schema's 'Optional historical date (YYYY-MM-DD)'.

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?

The description gives a specific verb and resource ('Get a full NBP ... exchange-rate table against PLN'), and 'full ... table' implicitly separates it from the singular nbp_exchange_rate. Siblings are never named, so differentiation relies on the agent inferring singular-vs-table from the tool name.

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?

It clearly explains the two operating modes (latest by default, or a historical date), which is useful internal guidance. But it never states when to prefer this over nbp_exchange_rate, nbp_rate_series, or nbp_convert, so sibling selection is left to inference from the names.

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