hmac

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

With no annotations, the description carries the full burden of behavioral disclosure, but it only states the basic operation. It does not disclose the output format (e.g., hex vs base64), determinism, or that it is a pure function with no side effects. This is a significant gap for a security-related tool.

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 description is a single, concise sentence that front-loads the core purpose. It contains no fluff or redundancy, making it easy to parse and understand quickly.

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?

The tool has no output schema, so the description is responsible for explaining the return value, but it only says 'Generate HMAC signature' without specifying the format or encoding. It also omits any mention of algorithm selection or error conditions, making it incomplete for an agent to predict the full behavior.

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 repeats the schema's parameter names ('text' and 'secret key') without adding new meaning. It does not elaborate on the 'algorithm' parameter, which is only partially covered by the schema (enum default). The description adds no guidance on parameter formats or valid values.

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 tool's function with a specific verb ('Generate'), a distinct resource ('HMAC signature'), and context ('for text with a secret key'). This distinguishes it from siblings like 'hash' or 'encode', which serve different purposes.

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 guidance is provided on when to use this tool vs. alternatives. It does not mention that HMAC is for authenticated messages, nor does it contrast with general hashing or encoding tools. The intended use case is implied but never explicitly stated.

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