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

The annotations already declare readOnlyHint=true and destructiveHint=false, so the description does not need to restate basic safety. However, it adds no additional behavioral context beyond the known single sentence, such as whether the opening balance is current-date-specific, what currency/account context applies, or what the response contains. It is safe but not transparent beyond the 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 a single, front-added sentence with no filler or redundant sections. Every word is functional, even though it is low-effort from an informational perspective.

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?

For a simple getter with full parameter coverage and read-only annotations, the schema provides enough to attempt a call. Yet because there is no output schema and the description does not mention what exactly the tool returns, the agent is left to infer the return shape from the parameter. A short note on the balance being the supplier's opening ledger balance would create a slightly more complete decision context.

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%; the input schema already documents itemId, companyName, and connectionRef with reasonable descriptions. The tool description adds no parameter-level nuance, but the baseline of 3 is appropriate because the schema carries the heavy lifing for parameter semantics.

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 is essentially a restatement of the title: 'Get Supplier Opening Balance' becomes 'Gets a supplier's opening balance.' It states the obvious action and resource but gives no additional specificity, so an agent is not helped to distinguish it from related siblings such as brc_get_customer_opening_balance or brc_list_supplier_op_bal_trans.

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?

There is no guidance about when to use this tool instead of alternatives such as brc_list_supplier_op_bal_trans or brc_get_supplier. The intended use is merely implied by the description, with no conditions, exclusions, or scenarios distinguishing this read operation from similar getters/lists.

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