Overview — Balance identity

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

Annotations already cover the read-only/safe profile, but the description adds genuinely non-obvious behavioral context: the check is health-independent, so a failure signals data inconsistency (stale read, missing category, uncounted account), and it discloses cost ('Costs three requests'). That is real added value beyond the structured fields.

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-loads the [READ] tag and the purpose, then adds interpretation and cost in tight sentences. No sentence is filler; each adds a distinct piece of information.

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?

An output schema exists, so return values needn't be explained, and annotations plus the description cover safety, cost, and interpretation. The only shortfall is the silent handling of plan_id, which an agent must guess.

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?

With one optional parameter at 0% schema description coverage, the description carries the burden but never mentions plan_id or what happens when it is omitted (default null). The name is fairly self-explanatory in a 'plan' domain, but the semantics of the default are left to inference.

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 precise verb (check) and resource (the plan's balance identity) and spells out the exact arithmetic relation it verifies (category balances + Ready to Assign = on-budget account balances + credit-card debt). This is specific enough to distinguish it from siblings like overview_cash_position or overview_budget_snapshot.

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 explicit when-to-use guidance ('Run it first in a review') and, crucially, tells the agent how to interpret the result — a tie means downstream numbers can be trusted, a mismatch means inconsistent data rather than bad budgeting. This steers invocation order and interpretation clearly.

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