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

With no annotations, the description carries the behavioral burden. It discloses fee structures (0%, 17%, 40%, 1.15%), available months per provider, and the minimum purchase threshold. It does not detail output format or error handling, but the core calculation behavior is well explained.

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 three tightly written sentences: purpose, Tamara plans, Tabby plans and minimum. No fluff, every detail earns its place, and information is front-loaded.

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?

The description covers input constraints well (region, currency, fee schedules, minimum). However, with no output schema, it does not describe what the tool returns (e.g., monthly payment, breakdown, or error behavior for unsupported months). This leaves a gap for an agent that needs to present results to the user.

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 baseline is 3. The description adds value by providing fee percentages and the minimum spend, which are not in the schema. It also clarifies the allowed months per provider, reinforcing the schema's enum 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 opens with a specific verb ('Calculates') and resource ('gold purchase installment plan'), naming the two providers (Tamara, Tabby). This clearly distinguishes it from sibling tools like get_gold_price and get_silver_price, which retrieve prices rather than calculate installment plans.

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 the tool is applicable: only in Saudi Arabia, with prices in SAR, and a minimum purchase of 200 SAR. It does not explicitly compare to alternatives, but the provider and plan details make the intended use obvious.

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