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

The description adds substantial behavior beyond annotations: explains that balance is a snapshot anchored to last sync, not a live read; details degradation to last-synced balance with realtime:false and warnings; and clarifies that errors surface as structured warnings rather than exceptions. This richly complements the readOnlyHint and idempotentHint 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 necessary operational detail about freshness, error handling, degradation, and response shape. It front-loads the core purpose and then layers caveats in a logical order with no 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 includes the response envelope { results, errors }. It covers parameter constraints, sync freshness, error modes, degradation behavior, and instructions for remediation. An agent has enough context to invoke the tool correctly and interpret results.

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 schema only shows account_ids as an array of strings, but the description adds critical meaning: 'Pass account_ids as an array (1–50)' and clarifies the response is per account id. Although the item format is not further detailed, the single parameter is well explained for practical use.

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 and resource: 'Returns the latest available balance per account id (GET /accounts/:id/balance)' and immediately clarifies the snapshot semantics. It clearly identifies the tool's unique function among many openfinance siblings without ambiguity.

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 gives explicit when-to-use guidance: if the balance is stale or disagrees with openfinance_list_transactions, run openfinance_force_sync then re-read. It also explains CREDIT account error cases and directs the user to reconnect the bank to restore consent, covering both alternatives and recovery paths.

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