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

With no annotations provided, the description carries the full burden and does so effectively. It discloses determinism, fixture verification, guest free-tier rate limits, the need for api_key to access member budget, and the return of a Guild-signed provenance envelope. This goes well beyond the bare minimum and provides valuable operational context.

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 dense but each sentence earns its place. It front-loads the primary purpose, then efficiently covers modes, operators, behavioral traits, and constraints. It includes two JSON schemas which are necessary given the generic input schema, though some could argue they make it slightly longer than ideal. Overall well-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?

The output schema is provided, and the description covers both usage modes, supported operators, rate limiting, provenance, and the payload contract. Given the tool's moderate complexity and the absence of annotations, this description leaves no significant gaps for an agent to select and invoke the tool 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?

The input schema only exposes a generic 'payload' object with additionalProperties true, giving no property-level meaning. The description compensates by embedding a dedicated JSON Schema for payload defining a, b, version, and constraint, and explains the semantics of each mode. This fully addresses the 0% schema coverage.

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 opens with 'Compare semantic versions or test a version against a constraint,' which is a specific verb+resource statement that clearly distinguishes it from siblings like json tools or table converters. It also details two operational modes (compare vs. test constraint), leaving no ambiguity about what the tool does.

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 clearly defines the two usage modes ('Either compare {a,b} or test {version,constraint}') and lists supported operators (>=, >, <=, <, =, ^, ~) and clause composition, giving clear context. However, it does not explicitly name alternatives or say when not to use this tool, so it falls just short of a 5.

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