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

No annotations are provided, so the description carries the full disclosure burden, and it discloses almost nothing: no statement about how whitespace, newlines, or multi-byte/emoji characters are treated, no confirmation that the operation is a pure read, and no note that both parameters are optional. For a counting utility these are the exact behaviors that matter.

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?

A single short sentence that front-loads the operation with no wasted words. It is efficient, though it is arguably too terse for the ambiguity it leaves unresolved.

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 tool with two overlapping undeclared parameters, no annotations, and no output schema, the description is not complete enough — an agent cannot tell which parameter to fill or what the result shape is. The trivial nature of the operation mitigates this only slightly.

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 nominally 100%, but both schema descriptions are generic placeholders ('Text to process', 'Input to process') and the description adds no meaning on top. Critically, it never explains the relationship between the two overlapping parameters 'text' and 'input', including which one is actually used — a real ambiguity the description should resolve.

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 states a specific verb and resource ('Count characters in a string'), so the operation is immediately clear. However, it does nothing to distinguish itself from very close siblings like x402-char-count, x402-byte-count, x402-word-count, or x402-length, which an agent must disambiguate by name alone.

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, no mention of alternatives, and no exclusion criteria. With several near-identical counting siblings, the absence of any routing hint leaves selection entirely to the agent's inference.

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