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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is clear. The description adds the expectation that the low-fee portfolio ends higher, but it does not describe output format, assumptions about contribution timing, or any computational caveats. This is acceptable because the output schema exists and annotations cover side effects.

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 with no filler: a clear summary followed by a concrete JSON example. The example is compact and demonstrates required and optional parameters effectively.

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 description plus the fully covered schema, annotations, and output schema give an agent enough to construct a valid call. The example supplies realistic values for all required fields. The main shortfall is lack of usage distinction from overlapping sibling tools, but that is captured under usage guidelines rather than completeness of invocation.

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 parameters are already documented. The description's example adds concrete value ranges and shows how required parameters combine, but it does not add meaning beyond what the schema already provides. A 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 ('Compare'), a precise resource (high vs. low management fees over time), and the key context (portfolio with monthly contributions). The example makes the intended calculation unambiguous and differentiates it from generic investment calculators among the 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 description gives no explicit guidance on when to choose this tool over siblings such as compare_investments or compound_interest. The example illustrates input format but does not state when this fee-focused comparison is appropriate or when another calculator should be used.

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