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

With no annotations, the description carries the full burden, and it does disclose one genuine behavioral trait: the 5 free trial calls per signed wallet (a cost/auth constraint). However, it says nothing about units, numeric precision, or what the response contains, which matters for a constant lookup.

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?

Very short and front-loaded, but the second half is marketing/pricing boilerplate with an emoji that does not help tool selection, and the first half is redundant phrasing.

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 trivial zero-argument constant tool with no output schema, the description should at minimum state the units and form of the returned value (e.g. J·s, scientific notation). It covers the payment model but leaves the actual output unspecified.

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?

The tool takes zero parameters and the schema is empty, so there is no parameter semantics to explain; the baseline of 4 applies.

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?

"Planck Constant: Constant planck" essentially restates the tool name and title without adding information — no value, no units, no return format. An agent can infer it returns the Planck constant, but the description itself contributes nothing beyond the identifier.

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 and no differentiation from physics-constant siblings such as x402-reduced-planck, x402-light-speed, or x402-electron-mass, which an agent could easily confuse with this tool.

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