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

With no annotations, the description carries the full behavioral burden, and it does disclose the output form (hex digest) and that keylen is optional with a default of 32. However, it omits the scrypt work factors (N, r, p) that govern the result and cost, which matter for reproducibility. It adds some value but is not complete.

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?

Front-loaded with the tool name and verb, then invocation and return value in two short sentences. Slight redundancy between 'from a password and salt' and 'Provide password and salt', but overall tight and well-ordered.

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?

No annotations and no output schema, so the description must stand alone; it covers the inputs and the return type adequately but leaves out scrypt cost parameters and the meaning of the string-typed keylen, both relevant for correct use.

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 100%, but the schema's own descriptions are tautological ('Salt to process'), so the schema contributes little. The description adds that password and salt are the inputs and that keylen defaults to 32, though it does not explain why keylen is typed as a string or what its valid range is.

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?

Names a specific verb and resource (derive a scrypt password hash from password + salt) and states the return value (hex digest). Clear on its own, but it never distinguishes itself from closely related derivation siblings such as x402-pbkdf2 or x402-hash-generator, so an agent must infer the choice.

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 description only says what inputs to provide ('Provide password and salt'), which is invocation mechanics, not usage guidance. There is no statement of when to prefer scrypt over pbkdf2/plain hash, no note on use cases, and no alternatives named.

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