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

Goes well beyond the annotations by explaining *why* readOnlyHint is false — the call is charged — which prevents an agent from misreading the flag as a side effect. It also discloses pricing, the x402/card-key payment path, the 25-free-call allowance, and that failed calls are free.

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?

Front-loaded with the core behavior and the example, with billing details trailing. Dense but every clause carries information; the pricing sentence is long but functionally necessary for an agent deciding whether to call.

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?

There is no output schema, and the description compensates by enumerating the return values (comparison result plus derived major/minor/patch). Combined with cost, prerelease handling, and the annotation rationale, an agent has everything needed to call 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 coverage is 100%, so baseline is 3, but the description adds real meaning: 'the first' identifies which parameter drives the next-version outputs, and the worked example shows both inputs are plain version strings ordered as a vs b.

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 ('Compare two semantic versions') and expands scope precisely: which is newer plus next major/minor/patch of the first. Prerelease handling is called out, and the example (a=1.10.0, b=1.9.3) disambiguates the semantics that trip people up.

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?

Explicitly frames the use case ('Use to decide whether an upgrade is a major change'), which orients the agent well. It doesn't name an alternative sibling, but none of the listed siblings overlap, so the omission costs little.

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