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

With annotations present, the description still adds meaningful operational context: the $0.001 USDC cost on Base per successful call and the x402 payment mechanism, which is not derivable from the schema or annotations. It doesn't explain the unusual non-read-only/idempotent=false hints, but the payment disclosure is genuinely useful.

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-loads the core operation, then the use case, then the billing detail — a sensible ordering with minimal waste. Slightly dense in the first sentence but every clause carries information.

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, so the description carries the burden of describing returns, and it does name the comparison result and the three next-version values. Payment mechanics are also covered; only exact output shape/format remains unspecified.

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% ('First version', 'Second version'), so the schema already defines both parameters. The description's 'compare two versions ... next versions of the first' does clarify that 'a' is the primary version, a small addition over the schema's neutral wording.

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') plus the exact returns (which is newer, next major/minor/patch of the first) and even covers pre-release handling. No sibling tool overlaps with version comparison, so disambiguation is trivially strong.

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?

'Use to decide whether an upgrade is a major change' gives a concrete use case, and the pre-release note implies when SemVer rules apply. It does not name alternatives or exclusions, but no sibling is a plausible substitute, so the guidance is adequate.

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