List accounts and balances

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

Goes well beyond the annotations by disclosing a side effect — 'The budget is synced with the server before reading' — which readOnlyHint/idempotentHint do not convey, and by explaining balance semantics: figures are as of TODAY, future-dated or scheduled transactions are excluded, and results may diverge from Actual's own account screen. That is exactly the kind of behavior an agent would otherwise get wrong.

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?

Front-loaded with purpose and return shape, then the freshness caveat and the agent-facing instruction. Every sentence carries information, though the enumerated field list is fairly dense and slightly redundant with itself ('amount' vs 'amountDecimal').

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 and no parameters, the description correctly takes on the job of describing the return payload (id, name, amount, amountDecimal, off-budget/closed flags, onBudgetTotal, total) and the syncing and balance-timing behavior. An agent has everything needed to call it and interpret results without surprises.

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 tool takes no parameters, so there is nothing for the description to disambiguate — the baseline of 4 applies. The prose spent on return fields is instead handled under transparency and completeness.

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?

States a specific verb and resource ('List every account in the Actual Budget file with its current balance') and immediately scopes the return set. No sibling tool does the same thing, and the description makes clear it is the roster-and-balance reader rather than a transaction or category lister.

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?

Gives clear context for when to reach for it and adds an actionable instruction ('Mention that if a balance looks off rather than assuming the budget is wrong'), which is genuine usage guidance. It does not, however, name an alternative or state exclusions (e.g., that it cannot filter by account or date).

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