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

With no annotations, the description carries the full load, but it does disclose a genuine behavioral trait: the whole text is returned when the separator is absent. It says nothing about the response shape, case sensitivity, empty-input handling, or why both 'text' and 'input' exist.

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 behavioral statement is front-loaded and compact. The trailing '🆓 5 free trial calls per signed wallet' is payment/marketing content that does not help an agent select or invoke the tool, so it slightly dilutes an otherwise tight 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 simple string utility with no output schema and no annotations, the behavioral sentence is adequate, but the undefined 'input' parameter and lack of response-shape context leave real gaps 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 coverage is 0% and no required params are declared. 'text' and 'separator' are loosely inferable from the prose, but the third parameter 'input' is completely unexplained, leaving an apparent redundancy between 'text' and 'input' that the description never resolves.

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?

States a specific verb+resource+behavior: returns the text preceding the first occurrence of a separator, with an explicit edge-case outcome. An agent can tell it apart from x402-substring-after/between by the wording, but the description never names those siblings to make the distinction explicit.

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 mention of the obvious alternatives (x402-substring-after, x402-substring-between) despite them being siblings. Usage is only inferable from the behavior description.

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