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

Annotations already mark this read-only and idempotent, but the description adds important behavioral context: the balance is a snapshot anchored to the last upstream sync, not a live read. It also discloses error handling (structured warnings, BALANCE_FETCH_ERROR, BALANCE_CONSENT_ERROR) and degraded behavior when the provider returns 5xx.

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 earns its place: freshness semantics, sync caveats, error modes, and the force_sync alternative are all directly useful. It is front-loaded with the core purpose before diving into edge cases.

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?

Despite having no output schema, the description tells the agent what to expect in the response (rows with updateDateTime/updatedAt and optional warnings), how to handle failures, and how to recover. For a read-only balance endpoint with a single parameter, this is complete enough for correct selection and invocation.

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 input schema only defines account_ids as an array of strings with no description coverage, so the description carries the burden. It adds that this must be an array and limits it to 1–50 items. It does not explain where account_ids come from, but the name and sibling context make that mostly inferable.

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?

States a specific verb ('Returns') and resource ('latest available balance per account id') and gives the exact endpoint. It is clearly distinguishable from siblings like openfinance_list_accounts or openfinance_get_accounts_detail.

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?

Explicitly tells the agent when to use openfinance_force_sync instead: if a recent movement is missing or the balance disagrees with transactions. It also explains what to do for credit consent errors, namely reconnect the bank.

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