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 fully covered and the bar is lower. The description adds that the tool also computes one-year interest and ending balance, disclosing the derived output set, but says nothing about edge cases such as zero-rate periods or invalid compounding values.

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 sentence of appropriate length, front-loaded with the primary computation and then the secondary outputs. No filler, no redundancy.

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 usefully states what is returned (APY, one-year interest, ending balance), and annotations cover the safety profile. Parameter documentation is complete via the schema. Only the lack of guidance on how this differs from the other interest/yield siblings leaves a small 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 100%, so all three parameters are already documented in the schema, which sets the baseline at 3. The description reinforces the meaning of 'nominal rate' and 'compounding frequency' and clarifies that 'deposit' is an example amount, but adds no format, unit, or range detail beyond what the schema states.

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 gives a precise verb ('Compute') and resource ('annual percentage yield'), and enumerates the exact inputs (nominal rate, compounding frequency) and outputs (one-year interest, ending balance). It is clear a compound-yield calculation, though it never explicitly distinguishes itself from close siblings like compound_interest, simple_interest, or rule_of_72.

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 when-to-use guidance and no mention of alternatives, which matters here because several siblings (compound_interest, simple_interest, rule_of_72) overlap in domain. The agent must infer that this tool is for the APY/APR-style effective yield rather than raw interest accumulation.

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