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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds the return content (interest, total value, annual-compounding comparison), which is useful context beyond annotations, but does not explain assumptions like the rate basis for the comparison.

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?

A single efficient sentence, front-loaded with the core action. No waste, though it is somewhat sparse for a tool that produces three distinct outputs.

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?

No output schema exists, so the description should frame the return values; it names the three outputs but does not specify how the compounding comparison is defined (same inputs? annual rate?). For a closed-world, read-only calculator with fully documented params this is adequate but not complete.

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 100% with clear per-parameter descriptions (annual rate percent, term in years, principal), so the schema does the heavy lifting. The description adds no additional parameter meaning or format constraints beyond the schema, so 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?

States a specific verb (Compute) and resource (simple interest, total value, compounding comparison). It describes the outputs as well. It does not explicitly name compound_interest as the sibling to distinguish against, leaving the simple-vs-compound boundary implicit.

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 guidance on when to use this versus compound_interest or the other finance siblings. The agent must infer that 'simple interest' implies non-compounding, with no explicit when/when-not statement.

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