calc_out_sum

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

With no annotations, the description must disclose behavioral traits. It explains that the calculation uses a configurable algorithm and fallbacks to environment variables, which is helpful. However, it does not mention return format, side effects, or whether it makes external calls.

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 succinct: two sentences plus a signature line. The most critical information (what it does, when to use, how parameters relate) is front-loaded. No unnecessary words.

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 output schema exists (return values are covered), the description adequately covers purpose, usage, and signature details. It lacks information about error handling or idempotency, but for a calculation tool this is acceptable.

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 schema already covers all 5 parameters. The description adds value by explaining the signature formula and fallback behavior for merchant_login and password1, which is not in the schema. This extra context aids correct parameter usage.

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: calculating the amount credited to the shop for a customer payment. It also provides context ('useful for showing the commission / final sum in checkout UI'), making it distinct from sibling tools like check_payment or verify_signatures.

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 gives a usage scenario (checkout UI) and includes the signature algorithm format, which guides proper invocation. However, it does not explicitly state when not to use this tool or how it differs from similar tools like check_payment.

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