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

With readOnly and idempotent already declared, the description still adds real content: the 19% capital gains tax is applied to both sides, the benchmark sources are named (finwire indices, NBP MIR, Ministry of Finance debt series), and it discloses that a sales-response test on the vendor's own series is included. The explicit exclusion of investment advice is a useful behavioural boundary.

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?

It is front-loaded with the metric name and symbol, which helps, but the body is one very long semicolon-chained sentence packed with Polish acronyms and multiple distinct sub-metrics. Splitting the component outputs into a short list would make it far easier to scan.

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?

Because an output schema exists, return structure need not be explained, and the description still supplies the calculation basis, tax treatment, data sources and each sub-metric included. The main remaining gap is the absence of guidance on when to select it versus related rate and deposit tools.

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% and the single parameter (history, 0-120, default 12) is fully described there. The description adds no meaning about the parameter, so the baseline of 3 applies with the schema doing all the work.

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 computed quantity: the tax-adjusted gap between first-year rates on named Polish retail bond families (OTS, ROR, DOR, TOS, COI, EDO, plus ROS/ROD) and three deposit benchmarks. That is far more specific than the name alone, though the verb is implicit and the sentence is a run-on rather than a clean statement of what the tool returns.

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 framed comparison (bonds vs deposits) and by the closing scope note that it reports a rate gap and is not investment advice. However, it never says when to pick this over neighbours such as get_bank_rates, get_interest_rates or get_retail_prices, so routing between siblings is left to inference.

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