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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely new operational facts: a 1 MB input cap and a paid x402 price of $0.003 USDC per call on eip155:8453. It stops short of describing rate limits or what the response looks like, particularly for algorithm='all'.

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 sentences, front-loaded with capability, then input/output encodings, then the size and pricing constraints. The long algorithm enumeration duplicates the schema enum and the title, which is mild waste, but the density of useful facts per sentence is high.

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?

With no output schema, the description should explain the shape of the result, yet it only names output encodings, not the return structure (e.g. whether 'all' yields a map keyed by algorithm). Constraints, pricing and encodings are covered, so it is adequate but not complete for an agent parsing the response.

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 0%, so the description must carry parameter meaning, and it does so only nominally: it restates the same algorithm, encoding and size vocabularies already present as enums in the schema. It adds a little value by clarifying that 'all' is a valid algorithm choice, but does not explain defaults or how 'data' is interpreted when inputEncoding is hex/base58.

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?

Starts with a specific verb+resource ('Hash text or bytes') and immediately enumerates the supported algorithm families, so the agent knows exactly what the tool computes. It is clearly distinct from the neighbouring hmac, encode and abi_encode tools.

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 implies usage (compute a digest of given data) but never states when to choose this over close siblings such as hmac (keyed hashing) or encode. No exclusions or preconditions beyond the implicit 1 MB cap are given.

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