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

Despite readOnlyHint and idempotentHint annotations, the description adds substantial behavioral detail: balances are snapshot values tied to the last upstream sync, not live reads; certain conditions produce structured warnings instead of throwing; and upstream 5xx or non-Open Finance connectors cause degraded rows. This goes well beyond the 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 dense but well-organized: core purpose first, then freshness caveat, then remediation, then parameter usage, then error behavior. Every sentence contributes necessary context, though the length is on the higher side and could be tightened without losing value.

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 tool with no output schema, the description covers invocation, parameter constraints, freshness semantics, error handling, and a remediation path. It does not describe the full response shape in detail, but it mentions key fields like updateDateTime/updatedAt and warning, which is sufficient for correct use.

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 does so by specifying that account_ids should be passed as an array and constrained to 1–50 items. While the schema already defines the array type and string items, the size constraint and usage hint add practical meaning.

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 clearly states a specific action and resource: 'Returns the latest available balance per account id' and gives the exact GET endpoint. It also distinguishes this tool by emphasizing the snapshot nature and explicitly referencing sibling actions like openfinance_force_sync and openfinance_list_transactions.

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 provides practical usage guidance: if the balance seems stale or inconsistent with transactions, run openfinance_force_sync and re-read. It does not explicitly compare with openfinance_get_accounts_detail or openfinance_list_accounts, but it gives enough context for the primary balance-fetching scenarios.

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