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

No annotations are supplied, so the description carries the full burden. It does disclose that the operation is 'Pure CPU, instant' and non-destructive by implication, and it outlines the returned metrics, but it says nothing about determinism, side effects, or whether the brute-force estimate is heuristic.

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?

It is short and front-loads the computation, which is good, but the final sentence is truncated mid-word, leaving an incomplete thought that an agent has to guess at. The remaining sentences are efficient.

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, stateless calculator with no output schema, the description does reasonably well by enumerating the returned values. However, the truncated usage clause leaves the intended decision ('judge secret or key randomness') and any interpretation guidance incomplete.

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?

There is a single parameter with 100% schema description coverage ('Text to measure'), so the schema already carries the meaning. The description adds no constraints on length, encoding, or character-set handling beyond that baseline.

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 names a specific computation (Shannon entropy) plus the shape of its results (bits per character, total bits, estimated brute-force space), so an agent knows exactly what it produces. It doesn't explicitly contrast itself with near-neighbours such as password_strength or check_password_strength, which is the only thing keeping it off a 5.

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 trailing clause 'Use to judge secret or key ran...' signals the intended use case, but it is cut off mid-word and gives no when-not guidance or named alternatives. Usage is implied rather than stated.

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