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. It discloses nothing about the formula assumptions, whether inputs are required or optional, rounding, error handling, or the nature of the returned value.

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 single sentence is far too short for a four-parameter financial calculation. This is under-specification rather than effective conciseness, leaving the agent without necessary context.

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 four-parameter tool with no annotations and no output schema, the description should explain the computation, clarify parameter meanings, and describe the result. It provides none of these, making it completely inadequate for correct 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 baseline is 3. The schema field descriptions are generic ('Face to process', 'Price to process'), but the structured fields still identify each parameter, and the tool description adds no further semantic value.

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 essentially a tautology: 'Yield To Maturity: Convert yield to maturity.' It restates the tool name without stating what is actually computed or what 'convert' means. An agent cannot distinguish this from siblings like x402-bond-yield, x402-current-yield, or x402-yield-dashboard.

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?

No when-to-use guidance, no prerequisites, and no alternatives are mentioned. The single sentence offers no context about fixed-income calculations or when this tool should be selected over related yield tools.

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