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

Annotations already cover readOnlyHint/openWorldHint/idempotentHint, but the description adds real behavioral context: it is derived ('Built from their detected paycheck and recurring bills — nothing to set up'), it declares its own failure mode when no paycheck exists, and it specifies return formatting (JSON, positive amounts, household currency, named by ccy). Auth/rate-limit details are absent, keeping this short of a 5.

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?

Purpose and output contents are front-loaded in the first sentence, and every subsequent sentence carries unique value (use cases, return format, failure fallback). The opening sentence is dense to the point of being a run-on with several comma-separated clauses, which costs it a point but not readability.

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 required parameters, the description compensates fully: it explains the return format and currency semantics, states what happens when the tool cannot produce a plan, and names the fallback tools. Nothing an agent needs in order to call this correctly is missing.

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 description coverage is 100% and both parameters carry their own descriptions including defaults and enum meanings, so the schema does the heavy lifting. The description echoes the concept ('next few paychecks', 'a share set aside toward bills that come less often') but adds no syntax, format, or default detail beyond what the schema already states.

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 names a specific output artifact (an interactive paycheck card) and enumerates exactly what it contains: bills/transfers due before the next check, the share set aside for less-frequent bills, and what's left. It is impossible to confuse with query or accounts, and it even states the precondition (a detected paycheck).

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 use cases ('budgeting by paycheck: what a check has to cover, how much to put aside each check, what's left after bills') and routes the agent elsewhere when it cannot apply: 'If no regular paycheck is detected it says so — then use query { recurring: true } and query { forecast: true }.' This is textbook when/when-not/alternative guidance.

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