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

No annotations are supplied, so the description carries the full burden. It does disclose the normalization (lowercasing), the return shape (list of bigrams), and the pricing/quota model ('5 free trial calls per signed wallet'), which is real behavioral context. It omits edge-case behavior such as empty input, punctuation handling, and whether pairs span sentence boundaries.

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?

Three short sentences, front-loaded with the definition and ending with the return value, with no redundant restating of the tool name. The quota/emoji sentence is marketing-adjacent but still operationally relevant.

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 single-purpose text transform with two optional params and no output schema, the description covers input, transformation, and output shape adequately. The remaining gap is the both-params-supplied precedence rule, which matters because both fields are optional and undocumented in the schema.

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 0% and both parameters are undocumented strings, so the description's line 'Provide text or input' is the only signal that these are alternative input fields rather than two separate arguments. That is genuine added meaning, but it never says which wins if both are supplied, leaving a real ambiguity unresolved.

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 and resource ('Split text into consecutive two-word pairs (bigrams)') plus the normalization applied ('lowercased'), so the transformation is unambiguous. It does not distinguish itself from near neighbors such as x402-bigram-similarity or x402-ngram, which the agent must infer from the 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?

The only guidance is 'Provide text or input', which hints that either parameter works but never states when to choose this tool over x402-ngram/x402-bigram-similarity, nor any exclusions or prerequisites. No when-not conditions are given.

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