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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description adds value by disclosing the batch response shape ('{ results, errors }') and enumerating the returned fields. This goes beyond the annotations without contradicting them.

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?

Three sentences deliver the core function, usage context, and parameter semantics without redundancy. The field enumeration is dense but directly relevant to what the agent needs to understand the return payload.

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 takes on the burden of explaining the complex return structure, listing key fields (interestRates, installments, CET, etc.). It also covers the batch shape and parameter constraints, making the tool well-specified for a read-only operation.

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 only defines loan_ids as an array of strings. The description adds the 1-50 count constraint and clarifies that these are loan contract IDs from a prior list, providing necessary context that the schema lacks (schema description coverage is 0%).

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 'Returns full loan contract detail by id' – a specific verb and resource. It also distinguishes from siblings by explicitly referencing openfinance_list_loans as the precursor, making the tool's unique role clear.

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 explicit usage guidance: 'Use after openfinance_list_loans to deep-dive on a specific contract.' It also specifies the parameter count limit ('Pass loan_ids as an array (1-50)'), leaving no ambiguity about when and how to use the tool.

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