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

Annotations already establish the safe read profile (readOnly, idempotent, non-destructive, closed-world), so the burden is lower. The description adds genuinely useful behavioural context beyond them: amounts are integers in minor units (45000 = 450.00) and dates follow the family time zone with YYYY-MM budget periods.

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 short sentences, each carrying non-redundant information, with the core output (balances per currency and base total) front-loaded. Slightly packed with formatting rules, but nothing is wasted.

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 no parameters, the description must carry the return-value burden, and it does explain the currency breakdown, base-currency total, rates, minor-unit amounts and date conventions. It could still state whether all accounts or only non-zero ones are returned, but coverage is otherwise solid for a simple read tool.

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 tool takes zero parameters, so the baseline is 4. The description correctly adds no parameter detail and instead spends its space on output-value conventions.

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 names the concrete resource and its contents: each account's balance per currency, a total in the base currency, and today's rates. That is specific enough to distinguish it from set_balance or list_accounts, though it never uses a verb and does not explicitly differentiate itself from near-neighbours like get_overview or get_analytics.

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 statement of when to call this tool versus the many siblings (get_overview, get_analytics, list_accounts, set_balance). The formatting conventions hint at what the tool returns but give no routing or exclusion guidance.

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