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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered and the bar is lower. The description adds the computational model (needs/wants/savings) and that results are monthly amounts, but omits validating behavior — e.g. what happens when needsPct + wantsPct exceeds 100, since savings is described as the residual.

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 tight sentences that front-load the primary use case before the custom-split variant. The trailing marketing URL is dead weight for an agent but does not obscure the definition.

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 is the only place return values can be explained, and it does so only loosely ('needs, wants and savings in monthly amounts') without stating the shape, currency formatting, or how the residual savings figure is derived. Adequate but with a clear gap for a tool whose entire purpose is producing a result.

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%, so all four parameters are already documented in the schema, and the enum on currency is fully self-describing. The description adds no syntax, unit, or constraint detail beyond the schema, so the baseline 3 is appropriate.

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 verb and resource — budgeting take-home pay — and pins the method to the 50/30/20 rule with three named buckets. It is clearly distinct from a plain income calculator, but it never names or contrasts a sibling (e.g. take_home_pay_calculator or savings_goal_calculator), so an agent must infer the boundary.

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?

'or set your own split, such as 60/20/20 for high-rent cities' implies when a custom split is appropriate, which is useful guidance. However, there is no explicit when-to-use-this-vs-alternative statement, no prerequisites, and no mention of what to do if the percentages don't sum sensibly.

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