Hash / HMAC

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

With no annotations, the description carries the full burden. It discloses output encodings (hex/base64/base64url), HMAC support, and a special 0x-form for keccak256, adding value beyond the schema. It omits the HMAC restriction for keccak256/sha3-256, but that is present in the schema.

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 concise and front-loaded, with the core purpose and algorithm list in the first sentence. The 'Args' summary at the end is slightly redundant given the schema, but it serves as a quick reference without bloating the overall length.

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 description covers the essential aspects: algorithms, HMAC, encodings, and the special 0x-form. Minor details like base64url input encoding and HMAC restrictions are missing but are captured in the schema. For a moderate-complexity tool with no output schema, this is sufficiently complete.

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%, so the baseline is 3. The description repeats parameter names and some values but adds little semantic detail beyond the schema. It even omits 'base64url' from input_encoding in the summary, relying on the schema for full details.

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: 'Compute a cryptographic digest' with a specific list of algorithms (sha256, md5, etc.). This distinguishes it from siblings like encode/convert, which focus on other transformations. The title 'Hash / HMAC' reinforces the purpose.

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 gives clear context for when to use the tool—for cryptographic hashing and HMAC—and lists input/output encoding options. It does not explicitly mention alternatives or exclusions, but the purpose is unambiguous enough for an agent to select it appropriately.

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