Calculates the SHA-256 cryptographic hash of an input string and returns its 64-character hexadecimal digest for integrity checks or payload identification.
Calculates the cryptographic SHA-256 digest of the input string and returns the resulting 64-character hexadecimal checksum.
| Name | Required | Description | Default |
|---|---|---|---|
| input | Yes | The string or payload to hash using SHA-256. |
Changes observed during successful MCP inspections.
v1.0.2Input schema / properties / input / descriptionPrevious value: -"Data to hash"New value: +"The string or payload to hash using SHA-256."v1.0.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It usefully discloses the return format (64-character hex) and that the operation is a pure digest of the supplied string, but says nothing about determinism guarantees, encoding of the input, or error behavior on non-string/empty payloads.
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?
One sentence, front-loaded with the operation and finishing with the output format. Nothing is padded or redundant.
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 one-parameter pure function with no output schema, the description covers the operation and the exact return shape, which is enough to invoke it correctly. The only gap is the absence of routing guidance relative to hash-adjacent siblings.
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 100% and the single parameter is already documented as 'The string or payload to hash using SHA-256.' The description adds no syntax, encoding, or size constraints beyond what the schema states, so the baseline 3 applies.
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 and resource ('Calculates the cryptographic SHA-256 digest') plus the exact output shape ('64-character hexadecimal checksum'), so it is unmistakable what operation occurs. It never names or contrasts a sibling (e.g., cyberchef_analyse_hash, cyberchef_to_hex), so differentiation is inferential rather than explicit.
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?
Usage is only implied by the verb 'Calculates... of the input string' — an agent can infer you call it when you need a SHA-256 hash. There is no explicit when-to-use, when-not, or pointer to a complementary tool such as cyberchef_analyse_hash for reversing/identifying hashes.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.