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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered; 'Changes nothing' merely restates it. The description adds useful conventions (minor units, date/month formats) but says nothing about what the computed plan actually contains or how projections are shaped.

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?

Dense but front-loaded: the core scenario is stated first, followed by encoding conventions. Every clause carries information, though the parenthetical stacking makes it slightly hard to parse on first read.

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, the description should describe what the plan returns (projection shape, dates, currency handling), and it does not. Input semantics are well covered, but for a simulation tool whose entire value is the returned plan, the return side is a real gap.

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 0%, so the description must compensate, and it largely does: it explains that cuts takes categoryId and a per-month amount in base currency, monthly is a per-month amount in goal currency, and last is a budget month. It also documents the integer/minor-unit and YYYY-MM/YYYY-MM-DD encoding conventions. The required 'id' parameter is left implicit, keeping it from a 5.

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 resource (a goal's plan) and clearly frames it as a hypothetical/what-if computation over three scenario levers (cuts, monthly, last). The title 'What if' plus 'Changes nothing' signals it is a simulation rather than a mutation, distinguishing it from apply_goal_cuts. It stops short of explicitly naming that sibling, so differentiation is inferential.

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 implies simulation use ('a goal's plan if...' and 'Changes nothing') but never states when to reach for this versus list_goals, update_goal, or apply_goal_cuts. No prerequisites or when-not guidance is given, so the agent must infer that this is the preview step before actually applying cuts.

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