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

No annotations are provided, so the description carries the full burden. It usefully discloses the paid cost of 0.001 USDC/call and the output format (hex), but omits payment mechanics, error behavior, and whether payment is mandatory despite the schema marking the payment parameter as optional.

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 short, waste-free fragments. Payment is front-loaded and the operation is stated immediately after. Slightly telegraphic, but appropriately sized for a simple utility.

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?

For a simple two-parameter paid utility, the description covers the operation, cost, and output format. However, it leaves the payment parameter undocumented and creates ambiguity by saying 'PAID' while the schema does not require the payment field.

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 description coverage is 0%. The description implies the `input` parameter is a string and hints at a payment cost, but it does not document the `payment` parameter's expected format, how payment is attached, or any constraints on `input`.

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 operation: computing the SHA-256 hex digest of a string. The resource and output format are clear, though it does not explicitly distinguish itself from sibling utility tools beyond the unique name.

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?

Provides no when-to-use guidance, no alternatives to consider, and no prerequisites beyond the stated per-call cost. An agent must infer the intended use case from the tool name alone.

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