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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds valuable behavioral context beyond annotations, including the batch response shape '{ results, errors }' and the array size limit of 1-50, which helps the agent anticipate error handling and payload constraints.

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 dense but efficient, starting with the core action and then listing return fields. The field enumeration is somewhat long, but each item conveys needed output structure with no fluff, earning a strong score.

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?

With no output schema, the description fully specifies the return values, including interestRates, charges, payments, warranties, installments, and batch shape. It also covers usage context and constraints, making it complete for a single-parameter read-only tool.

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 0%, so the description must compensate. It does by explaining that `loan_ids` are the identifiers and specifying the array limit '1-50.' This adds practical meaning beyond the bare schema type of array of strings.

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: 'Returns full loan contract detail by id' with the specific endpoint GET /loans/:loanId. It distinguishes the tool from siblings like openfinance_list_loans by focusing on detailed contract data rather than a list of loans.

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 explicitly instructs to 'Use after openfinance_list_loans to deep-dive on a specific contract,' naming the sibling tool and the intended workflow. This provides clear when-to-use guidance and implies an alternative usage pattern.

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