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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds meaningful behavioral context beyond these: the batch execution model with a `{ results, errors }` shape, which implies partial failures and error handling. It also clarifies the input is an array, aligning with the batch behavior. This enriches the transparency without contradicting annotations.

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 with information: purpose, endpoint, detailed return fields, usage guidance, and batch shape. It is front-loaded with the main verb and resource, then details output. While the field list is long, it serves to clarify the complex return payload in the absence of an output schema. It is structured and not bloated.

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 absence of an output schema, the description appropriately enumerates the key fields (interestRates, contractedFinanceCharges, balloonPayments, warranties, installments schedule, etc.). It also covers usage context and batch behavior. The sole missing element is the explicit type of each a element in `loan_ids`, but overall this is complete for a single-parameter tool with a rich response.

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 must compensate. It explicitly names the parameter `loan_ids`, specifies its type (array), and adds a size limit (1-50). However, it does not explicitly state that each element should be a loan identifier string, though this is strongly implied by the tool name and context. This is good compensation but could be slightly more precise.

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 and resource: 'Returns full loan contract detail by id.' It clearly differentiates from siblings like openfinance_list_loans (which lists all) and openfinance_get_accounts_detail by focusing on loan-specific contract detail. The mention of the REST endpoint (GET /loans/:loanId) further anchors its purpose.

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?

Explicitly states 'Use after openfinance_list_loans to deep-dive on a specific contract,' providing a direct usage sequence with an alternative tool. It also specifies a batch constraint ('Pass loan_ids as an array (1-50)') and describes the response shape, giving clear operational guidance.

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