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

Beyond the readOnly/idempotent annotations, the description reveals important behaviors: the result is a snapshot tied to the last upstream sync, updateDateTime is not a live timestamp, credit accounts may return structured warnings instead of throwing, and upstream 5xx or non-Open Finance connectors degrade the row. No contradiction with 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 long but every sentence adds distinct operational value: freshness semantics, sync workflow, error handling, and degradation conditions. It is front-loaded with the core action and endpoint, then layers necessary caveats in a logical order.

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 there is no output schema, the description adequately explains the response's row-based nature, key fields (updateDateTime/updatedAt), and error/warning representations. It covers freshness, retry flow, credit-specific failures, and upstream degradation, making the tool safe to invoke without additional 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?

With 0% schema description coverage, the description carries the full burden for the only parameter. It specifies that account_ids must be an array with a 1–50 item limit, which is not present in the schema. This materially helps an agent construct valid input.

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 ('Returns'), a clear resource ('latest available balance per account id'), and the exact endpoint ('GET /accounts/:id/balance'). It also distinguishes the tool from a live read and from openfinance_list_transactions, making its purpose unmistakable even among many siblings.

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 gives explicit conditional guidance: if the balance is stale or disagrees with transaction sums, run openfinance_force_sync and re-read. It also explains error scenarios for credit accounts. It does not explicitly contrast with openfinance_list_accounts or other balance-related siblings, but the primary alternative workflow is clearly identified.

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