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

The description goes well beyond the readOnly/idempotent annotations: it explains that updateDateTime/updatedAt is the sync instant, not a live read; describes BALANCE_FETCH_ERROR and BALANCE_CONSENT_ERROR; and details row degradation to realtime:false with warnings. These are non-obvious behaviors the agent needs to interpret results correctly.

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 long, but the length is justified by the complex error, degradation, and freshness semantics. It is front-loaded with the core purpose and endpoint, and each subsequent sentence adds meaningful operational detail rather than filler.

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?

Given that there is no output schema, the description covers the response shape, the errors array structure, per-row warning behavior, and the realtime flag. It also references sibling tools for the recovery path. Nothing essential for invoking or interpreting the tool is missing.

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?

With 0% schema coverage, the description compensates by telling the agent to pass account_ids as an array and constraining it to 1–50 items. It does not specify the exact format of each account id string, but for a single required parameter this is nearly sufficient.

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 the latest available balance per account id' with the exact endpoint. It clearly differentiates this from list-type tools and ties the snapshot semantics to the sync anchor rather than a live read.

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?

It explicitly tells the agent when to use the alternative: if the balance is stale or disagrees with openfinance_list_transactions, run openfinance_force_sync and re-read. It also covers credit-account error cases and when degradation occurs, giving clear decision context beyond a simple tool description.

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