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

The description goes well beyond the readOnly/idempotent annotations by disclosing that the balance is a snapshot anchored to the last upstream sync, that realtime may be false, and that rows can degrade to last-synced data with a warning instead of throwing. It also explains consent and provider error modes. 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 clause adds operational value, and the core endpoint and snapshot caveat are front-loaded. The dense parentheticals about error modes and degraded rows make it less scannable, but they are not 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?

With no output schema, the description still specifies the response shape and key row fields (updateDateTime/updatedAt, realtime, warning). It covers error rows, degradation, consent issues, and recovery steps, leaving little an agent needs to infer in order to invoke and interpret the call correctly.

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 coverage is 0%, so the description carries the burden for account_ids. It adds that account_ids must be an array of 1–50 items and describes what the IDs represent. It stops short of saying where the account IDs come from (e.g., list_accounts), but the single parameter is adequately explained.

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 precise action and resource: 'Returns the latest available balance per account id (GET /accounts/:id/balance)'. It clearly identifies what is fetched and the endpoint, making it easy to distinguish from list/transaction 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?

It provides explicit guidance for stale or inconsistent balances: run openfinance_force_sync and re-read. It also explains when CREDIT accounts return BALANCE_FETCH_ERROR or BALANCE_CONSENT_ERROR and how to recover, so an agent knows exactly when this tool is appropriate and what to do instead.

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