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

With no annotations provided, the description carries the full burden of behavioral disclosure, and it says nothing about what the tool does, returns, or in what units. An agent learns no more about the tool's behavior than it could from reading the name, and there is no output schema to clarify the return 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 description is only five words, but this is under-specification rather than genuine conciseness. No sentence earns its place because no sentence conveys useful information — the structure mimics a label rather than a tool definition.

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?

Although the tool is low-complexity (zero parameters, no nested objects), the essential information an agent needs is absent: what value is returned, in which units, and how this differs from x402-reduced-planck. The description does at least name the physical constant, giving the agent a minimal anchor for guessing the 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?

The input schema has zero properties with 100% schema description coverage, so per the rubric the baseline is 4 for parameter semantics. There are no parameters to document, and the description's failure to add parameter meaning is irrelevant because none exist.

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 'Planck Constant: Constant planck' is a tautology that merely restates the tool name/title without any verb or action. It never states that the tool returns the Planck constant value, so an agent is left to infer the purpose from the name alone. It does at least identify the resource (the Planck constant), which keeps it above a bare 1.

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 guidance is given on when to use this tool, and crucially, the sibling tool x402-reduced-planck exists as a close alternative that is never mentioned. An agent cannot distinguish between retrieving the Planck constant (h) versus the reduced Planck constant (ħ) because no comparison or exclusion is provided.

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