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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions input size limits and the ed25519 parameter requirement, but it does not disclose whether the operation is read-only, whether it has side effects, what the return value looks like, or any error/edge-case behavior. For a tool with no annotation coverage, this is a significant gap.

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?

The description is compact and front-loaded with the core action, then lists the check types and the key constraint. Every sentence adds information, though the list of check types could arguably be more structured.

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?

Given no output schema and no annotations, the description is incomplete for a tool with 4 parameters and multiple algorithm variants. It does not describe the return value, error behavior, or how the different checks behave beyond the ed25519 parameter note. An agent would likely need to inspect external documentation or experiment to use it correctly.

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%, so the description must compensate for the schema's lack of parameter documentation. The description explains that 'check' selects the algorithm and that 'ed25519' additionally requires 'public_key' and 'signature', but it does not explain the format or constraints of 'input' beyond the 64 KB limit, nor the meaning of the other check types' parameters. Partial compensation, but not enough.

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?

The description states a specific verb ('Runs') and resource ('one check over supplied input'), and enumerates the supported check types. It distinguishes the tool from siblings by naming the check variants, though it doesn't explicitly contrast with a sibling tool.

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 by listing the check types and noting the ed25519-specific parameters, but it does not explicitly state when to use this tool versus alternatives or when not to use it. The context is clear enough for an agent to infer basic usage, but explicit guidance is missing.

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