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

With no annotations, the description carries the full burden, but it omits key behavioral details: output format, return type, encodings for password/salt, default iterations, and keylen units. It says what the tool does but not what the agent should expect back or what constraints apply.

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?

Two short sentences front-load the purpose and then describe the expected inputs. The redundant 'Pbkdf2:' prefix and repetition of 'password' are minor, so it is concise but not perfectly lean.

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?

This is a cryptographic tool with no annotations, no output schema, and an empty input schema. The description does not cover return values, defaults for iterations/keylen, input encodings, or validation requirements, leaving the agent without enough information to invoke the tool correctly.

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 description names password, salt, and optional iterations/keylen, but these are not present in the input schema, which has no properties. While it adds some semantic intent, it contradicts the actual schema and omits types, defaults, requiredness, and units, so an agent cannot construct a valid call from the schema.

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 clearly states the operation: derive a PBKDF2-SHA256 key from a password and salt. This identifies the specific algorithm and resource, which helps distinguish it from related siblings like x402-scrypt, though it does not explicitly name or contrast any sibling.

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 guidance on when to use this tool vs alternatives, no prerequisites, and no usage exclusions. The algorithm name is the only implied signal, leaving the agent to infer when PBKDF2 is the right choice.

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