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

No annotations are provided, so the description carries the full burden. It does add a genuinely useful behavioral attribute — the x402 price of $0.01/call in USDC on eip155:8453 — which an agent needs to know before invoking. However, it says nothing about the return shape (percentage vs. decimal, rounding) or error behavior for edge cases like zero/negative years.

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 first sentence is well front-loaded and earns its place. The second sentence ('Use this when an agent needs to compound annual growth rate, time-normalized') is circular and adds little, wasting space before the otherwise useful pricing note.

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?

For a simple three-parameter pure-calculation tool with full schema coverage and no output schema, the description covers what it computes, its inputs, and its cost. It is essentially complete, with only minor gaps around output format that an agent could reasonably infer.

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 three parameters are already documented structurally. The description names the same concepts (initial value, final value, number of years) without adding format, unit, or validation detail beyond the schema. This is the baseline case where the schema does the heavy lifting.

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 and resource ('Calculate the compound annual growth rate') and defines the three inputs precisely, plus frames it as 'the standard way to annualize returns.' It distinguishes itself conceptually from a plain ROI or compound-interest calculation via the annualization framing, though it never names those siblings 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?

The only usage cue is 'Use this when an agent needs to compound annual growth rate, time-normalized,' which is essentially a restatement of the tool's own purpose. No guidance on when to prefer this over calculators_compound_interest_calculator or finance_roi_calculator, and no prerequisites or exclusions.

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