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

With no annotations, the description carries the full burden. It usefully discloses that the tool is free/no payment, deterministic, and returns hex, but says nothing about input size limits, invalid-algorithm behavior, encoding assumptions, or error handling. Adequate but incomplete for a zero-annotation 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?

Three tight fragments, front-loaded with the cost signal (FREE) and the core capability. Minor redundancy because the text closely mirrors the title, but no sentence is padded or buried.

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?

There is no output schema, yet the description covers the return format (hex) and the deterministic nature, which is what an agent most needs here. The remaining gap is the failure mode for an unsupported algo and the default when algo is omitted, both of which remain unspecified.

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, but the description genuinely adds value: the schema only shows "e.g. 'sha256'" for algo, while the description reveals that sha512 and sha3-256 are also supported. That materially expands what the agent knows about valid algo 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?

States a specific verb+resource (SHA-256 hash/digest of a text string) and names the supported algorithm variants (sha512, sha3-256) plus the output format (hex). This clearly separates it from sibling utilities like u_base64, u_hex, and u_jwt without needing to open any schema.

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 explains how to invoke it ('use over MCP or POST /u/sha256 over HTTP'), which is transport guidance rather than when-to-use guidance. It never says when to prefer this over sibling encoders/hashers or u_hex, so usage selection is only implied by the tool's name.

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