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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety behavior is covered. The description usefully adds an interpretive claim about results (the gap comes mostly from compounding, not extra contributions), but says nothing about permissions, limits, or computation assumptions beyond the return rate.

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, front-loaded with the purpose before the example. The embedded JSON example is compact and directly usable, though the qualitative result claim consumes space that could have carried usage guidance.

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 6 fully documented parameters, an output schema, and complete annotations, the description needs only to frame purpose and scenario, which it does. Minor gaps are the absence of sibling routing and of any caveats about assumptions in the comparison model.

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%, with each parameter documented including constraints (retire must exceed compare, compare greater than start). The example reinforces the parameter roles but adds no semantics beyond what the schema already provides, so the 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?

States a specific verb (compare) and resource (investing the same monthly amount at an early vs later age) and frames the outcome as 'what the delay costs by retirement'. It is clearly distinguishable in substance from siblings like compound_interest, though it never names an alternative to differentiate explicitly.

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?

There is no statement of when to choose this tool over compound_interest, compare_investments, or latte_factor, and no prerequisites or exclusions are given. The example implies the intended scenario but does not guide tool selection.

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