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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), so the bar is lower. The description adds genuinely valuable behavioral context: 'Monthly values represent movements rather than monthly balances' — a semantic warning that prevents an agent from misinterpreting returned numbers. Consistent with the read-only annotation; no contradiction.

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?

Two sentences with zero waste. The first front-loads the core purpose; the second delivers the critical movement-vs-balance clarification. Every sentence earns its place, and nothing is repeated from the annotations or schema.

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?

There is no output schema, so the description carries the burden of explaining return values. It covers the key semantic trap (movements vs balances) but does not describe the ledger's structure or fields, which an agent would need to interpret results. Adequate for a moderate-complexity read tool, but with a clear gap around return format.

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 100%, with all three parameters (ids, companyName, connectionRef) documented in the schema — the connectionRef note is particularly rich. The tool description itself only loosely maps to the ids parameter ('supplied account IDs') and adds no format, syntax, or relationship details beyond the schema. Baseline 3 is appropriate.

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: 'Returns nominal-account ledgers for supplied account IDs.' The plural scope ('IDs') distinguishes it from the close sibling brc_get_nominal_account_ledger_by_id, though the description does not explicitly contrast them. Slightly held back from 5 because the differentiation from the singular sibling relies on the name rather than an explicit statement.

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?

No guidance on when to use this tool versus brc_get_nominal_account_ledger_by_id (singular) or brc_grouped_nominal_accounts_report. The description provides no selection criteria, prerequisites (e.g., obtaining account IDs first), or exclusions. The connectionRef parameter note in the schema gives session-management context but not tool-selection guidance.

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