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

Even though annotations already mark this as read-only and idempotent, the description adds substantial behavioral detail: balances are sync-anchored snapshots, `updatedAt` is the sync instant rather than live time, certain errors degrade to warnings with `realtime: false`, and specific Pluggy error codes are disclosed. This goes well beyond the structured 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 every sentence earns its place: purpose, endpoint, snapshot caveat, remediation path, parameter format, error modes, degradation behavior, and response envelope are all covered without fluff. It is front-loaded by stating what the tool returns 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?

For a tool with no output schema, the description is remarkably complete: it gives the response shape, error row structure, degraded-mode fields, and the explicit instruction to force-sync before re-reading. An agent has enough information to invoke it correctly and interpret the result without further schemas or external knowledge.

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%, but the description fully compensates for the single `account_ids` parameter by specifying that it must be an array of 1–50 account IDs. It also ties the parameter to behavior, noting per-account rows and CREDIT-account error modes. The description carries the entire semantic burden and does so effectively.

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 names the endpoint. It is immediately distinct from sibling tools like openfinance_list_transactions and openfinance_get_accounts_detail because it focuses solely on balance retrieval, with no ambiguity about what it returns.

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 gives clear operational context: it explains the snapshot nature of the data, when staleness can occur, and explicitly instructs to call openfinance_force_sync and then re-read when the balance seems stale or disagrees with transactions. It doesn't explicitly contrast itself with every potentially overlapping sibling, but the primary usage condition is clear.

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