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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safe read nature is covered. The description itself adds no behavioral context beyond restating the read operation: it does not mention what the opening balance represents, how it is calculated, what period it refers to, or what the return payload contains.

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 short sentence with no wasted words and is front-loaded with the core action. It is appropriately brief for a simple read operation, though the brevity leaves several contextual gaps that a longer description could have addressed.

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 and a terse description, the agent gets no information about the return value shape, such as amount, currency, or period. It also lacks any pointer to related tools like brc_list_customer_op_lal_balance_transactions or how an empty balance should be interpreted. Despite simple required parameters, this is insufficient guidance for navigating the large sibling family.

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 covers all parameters with descriptions, including the important semantics of connectionRef. Since schema_description_coverage is 100%, the baseline of 3 applies. The tool description itself adds no parameter meaning beyond saying the balance is for a customer, which is marginally tied to itemId and companyName.

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 states a specific verb and resource: 'Gets a customer's opening balance.' This is clear and distinguishes the target data (customer opening balance) from plainly getting a customer. However, it does not explicitly distinguish itself from overlapping siblings like brc_get_supplier_opening_balance or brc_list_customer_op_bal_trans, so it misses the top score.

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 no guidance on when to use this tool versus alternatives. It does not mention related tools such as brc_list_customer_op_bal_trans for transactions or brc_get_supplier_opening_balance for suppliers, and it offers no prerequisites or context for when this call is appropriate.

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