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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds genuinely non-structured facts: it is free, requires no key, is computed on this server (not fetched), and nothing is stored. It does not discuss failure modes or input limits, keeping it short of a 5.

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 sentences, front-loaded with the most decision-relevant fact ('FREE, no key'), and no filler. The middle clause about agents and the coordination layer is slightly verbose but still informative.

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?

No output schema exists, but the description states the return format (64 hex characters), which is the key missing piece for this utility. For a stateless two-parameter hash function with full schema coverage, this is complete enough; only edge cases (empty input, max length) are unaddressed.

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% with both parameters documented, including the enum and the sha256 default, so the schema does the heavy lifting. The description restates the algorithm options and confirms the 64-hex output but adds no format or constraint detail beyond 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?

States a specific verb+resource ('the sha256 (or keccak256) digest of a text'), names both supported algorithms, and specifies the exact output shape (64 hex characters). No sibling tool in the list performs hashing, so it is trivially distinguishable.

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?

Gives clear usage context: agents/registries/coordination layer use it to verify that the server returns content verifiable by code, and notes it also works as a plain utility. It does not, however, state when NOT to use it or point to any alternative tool for related tasks.

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