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

No annotations are provided, so the description carries the full behavioral burden, yet it only discloses a billing/rate-limit detail (5 free trial calls per signed wallet). It says nothing about computation method, edge cases (negative or zero-length periods), whether a wallet signature is required to invoke it, or what the response contains.

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 text is brief and front-loaded with the purpose, but it is brief because it is under-specified rather than efficient. The leading "Annualized Return:" label duplicates the tool name without adding information, and the emoji pricing line occupies a full third of the description.

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 three-parameter calculation tool with no annotations, no output schema, and zero schema coverage, the description supplies nothing an agent needs to call it correctly. Neither the input formats nor the returned quantity are described.

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 0% and three string parameters (start, end, years) are completely undocumented in both schema and description. The agent cannot tell the expected format (ISO dates? unix timestamps? numeric strings?), whether start/end are optional or mutually exclusive with years, or how the two modes interact.

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 is effectively a restatement of the tool name: "Annualized Return: Annualized return calculation." It never says what inputs are annualized (price series? cash flows?) or what the output represents, and it draws no distinction from the many nearby siblings such as x402-cagr, x402-irr-calc, x402-roi, or x402-holding-period-return.

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, no prerequisites, and no mention of any alternative tool for return calculations, despite the sibling list containing several overlapping finance tools. The only contextual sentence is a pricing note about free trial calls, which does not help the agent decide whether to select this tool.

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