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

The description goes far beyond the read-only/idempotent annotations: it explains the snapshot is anchored to the last upstream sync, that updateDateTime reflects sync time not live time, and it details BALANCE_FETCH_ERROR, BALANCE_CONSENT_ERROR, and degradation-to-warning behavior for 5xx or non-Open-Finance connectors. This is rich, non-obvious behavioral context.

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 each sentence carries consequential information: freshness semantics, when to force a sync, array bound, and error/warning behavior. The primary purpose is front-loaded, and the additional details are organized in a readable sequence, though some sentences are dense and could be tightened.

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?

For a single-parameter read-only tool with no output schema, the description covers the core return semantics, data freshness caveats, error conditions, and remediation steps. An agent has enough information to correctly invoke the tool and interpret unexpected results, making the definition effectively complete.

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 0%, so the description must compensate. It clarifies that account_ids is an array and adds a 1–50 size constraint, but it does not explain where these IDs come from or that they correspond to accounts previously returned by openfinance_list_accounts. The endpoint path helps slightly, but the parameter semantics remain partially under-specified.

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 opens with a specific verb and resource: 'Returns the latest available balance per account id' and cites the exact endpoint. It clearly distinguishes this balance snapshot tool from transaction/list/mutation siblings by naming openfinance_list_transactions and openfinance_force_sync.

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 states when to use the tool and what to do when results seem stale: if a recent movement is missing or the balance disagrees with openfinance_list_transactions, run openfinance_force_sync and re-read. This gives an agent a concrete decision path rather than leaving usage to inference.

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