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, and it discloses nothing: not the formula used, not the units expected (seconds? kg? percent?), not whether inputs are strings or numbers, and not what is returned. With no output schema either, the agent has no way to predict the result shape.

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?

It is short, but that brevity is under-specification rather than conciseness: the single sentence contains zero information beyond the name. No front-loaded statement of what the tool computes.

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 parameterized physics calculator with no annotations, no output schema, and three loosely documented string parameters, the definition omits everything an agent needs: units, expected type, formula, and return value.

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 of 3 applies per the rubric. However, the schema descriptions are generic placeholders ("Time to process", "Initial to process", "HalfLife to process") and the tool description adds nothing, so the effective meaning of time/initial/halfLife—especially units and formats—remains ambiguous.

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 "Radioactive Decay: Radioactive Decay", which simply restates the tool name/title with no verb or scope. An agent learns the domain but not what operation is performed (compute remaining mass? activity? elapsed time?) or how it differs from siblings like x402-half-life and x402-decay-constant.

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 indication of when to use this tool versus alternatives. With closely related siblings such as x402-half-life, x402-decay-constant, and x402-doubling-time in the catalog, the absence of any routing guidance is a real gap.

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