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

With no annotations, the description carries the full behavioral burden. It does disclose that inputs are discarded, but it fails to state the return value/type, error behavior, network/disk access, or side effects. The 10-parameter schema with no output schema demands more disclosure for safe invocation.

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?

Five words are concise but under-specified: 'CityHash128 hex length, input discarded' is a fragment requiring inference. It omits critical information and is not front-loaded with a clear action, making it closer to under-specification than efficient concision.

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 tool with 10 optional parameters, no output schema, and no annotations, this description is far too incomplete. An agent cannot confidently determine what invoking city128 will return, what arguments are meaningful, or how it relates to sibling tools. A minimal complete definition would state the return value and explicitly say all parameters are ignored and optional.

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%, so the baseline is 3 and the schema already documents each parameter. The description adds no per-parameter meaning, and its blanket 'input discarded' conflicts with schema hints like 'HTTPS URL to normalize or cite' and 'check for agent readiness', reducing confidence that the schema reflects actual behavior.

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 is a noun fragment, not a statement of what the tool does: 'CityHash128 hex length, input discarded'. It hints at an output—the hex length of a CityHash128 digest—but lacks a verb such as 'returns' or 'computes'. 'Input discarded' is ambiguous and does not clarify whether inputs are ignored, validated, or used and then dropped.

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?

There is no guidance on when to call this tool or when to prefer a sibling such as normalize-url, validate-json, or domain-shape. The description states no use case, prerequisites, or exclusions; 'input discarded' is a behavioral note rather than usage context.

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