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

Annotations only indicate mutability (readOnlyHint=false) but provide no lifecycle detail. The description adds that the expense is shown under Upcoming until logged or skipped, and that amount must be positive. This is useful behavioral context beyond what annotations or schema state.

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?

Two sentences with zero filler. The core concept is front-loaded and the caveat about positive amount is included without redundancy.

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 creation tool, the description explains the purpose and lifecycle adequately. An output schema exists, so return details are covered. Missing explicit parameter semantics is a minor gap but does not undermine core usability.

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 57%, but the description adds no parameter-level guidance beyond restating that amount is positive (already in schema). It fails to clarify name, note, category_id, or how account_id interacts with target_date. The moderate coverage is not compensated, leaving ambiguity for agents.

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 clearly states the tool adds a one-off planned expense with concrete examples (flight, fee, gift), explains it appears under Upcoming until resolved, and distinguishes it from recurring or regular transactions. It is specific and unambiguous.

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 phrase 'a one-off you know is coming' implies usage for non-recurring future expenses and differentiates from add_recurring_rule. It also hints at lifecycle ('until it is logged or skipped'), pointing to resolve_planned_expense. However, it doesn't explicitly name alternatives or provide exclusion criteria, so it falls short of a perfect score.

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