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

Annotations already establish read-only and idempotent behavior, and the description adds the meaningful disclosure that no external rules or identifiers are involved. This tells an agent the tool is a pure arithmetic function with no hidden business logic, going beyond the annotation signal.

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 short sentences and immediately front-loads the operation and its limits. Every sentence adds scope information, and there is no filler beyond the repeated bilingual title.

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 simple two-parameter arithmetic calculator with read-only annotations, an idempotency hint, and an output schema, the description covers the operation and exclusions sufficiently. The only real gap is the implicit rather than explicit parameter order, but the tool name and parameter names reduce the risk of confusion.

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 0%, so the description needed to define the parameters, but it only says 'numerator by denominator' without explicitly stating that loan_agorot is divided by property_value_agorot. The parameter names and title make the mapping inferable, but the description itself does not fully compensate for the empty schema descriptions.

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 uses the specific verb 'divide' and names the resource as the loan-to-value ratio, making the core operation clear. It also disclaims regulatory caps and eligibility verdicts, which separates it from the more judgment-heavy sibling tools, though it does not name a sibling explicitly.

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 negative constraints ('No regulatory caps, eligibility verdict, fallback rates or customer identifiers') imply this is the tool to use for a raw ratio calculation rather than a full lending decision. However, there is no explicit when-to-use guidance or direct comparison to calculate_payment/calculate_pti_ratio.

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