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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering the safety profile. The description adds that it is a deterministic calculation producing a fixed monthly amount, but does not disclose internal assumptions like compounding frequency. This is acceptable given annotations but not especially rich.

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?

The description is a single sentence that is front-loaded with the inverse relationship, followed by a concise definition of the calculation. Every word earns its place; no redundant or filler content.

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?

The tool is simple, has an output schema (per context signals), and the description conveys the core purpose. It lacks explicit assumptions about compounding or contribution timing, but for a straightforward calculation tool the description is adequate and complete enough without over-burdening.

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 the schema already documents all parameters clearly. The description adds minimal value by referencing the optional starting balance, but the schema already includes that detail. Baseline 3 applies.

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 computes the fixed monthly contribution needed to reach a target future value. It explicitly calls out being the inverse of the 'contributions' tool, which differentiates it from siblings.

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 'inverse of contributions' wording implies when to use this tool (when you know target value and need monthly contribution), but it does not explicitly name alternatives or exclusion criteria. Sibling tools like annuity-payment may overlap, so more direct guidance would improve.

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