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

Beyond the readOnlyHint annotation, the description discloses specific behavioral details: repo rate plus 8 percentage points, specific rates for 2026 half-years, 3 grace days, floors, and the rejection condition for dated estimates outside implemented history. This is rich, non-obvious behavioral information that aids the agent in understanding how the tool behaves.

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?

The description is two sentences, compact, and front-loaded with the primary purpose. Every sentence carries substantive information (rates, thresholds, rejection behavior) without unnecessary verbiage.

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?

Given the tool's complexity (5 parameters, no output schema), the description covers key aspects: calculation inputs, rate types, and a critical limitation. It does not describe return format, but that may be less critical for a calculation tool. The behavioral notes provide sufficient context for most usage scenarios.

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?

The description provides some context for parameters (e.g., repo rate, grace days, thresholds) but does not directly explain each parameter's role. Schema coverage is 60%, meaning some parameters are not described in the schema or the description. The description adds value but not enough to fully compensate for the coverage gap.

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 clearly states the tool's purpose: estimating the Czech penalty/interest for a late payment or filing. It names the specific resource (penalty/interest) and verb (estimates), and includes rate details that immediately distinguish it from sibling tools.

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?

The description provides clear context for when to use the tool (for late payment or filing penalty estimates) but does not explicitly mention alternatives or when not to use it. It does note a key constraint about dated estimates being rejected outside implemented history, which helps guide usage.

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