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

With no annotations, the description carries the full burden of behavioral disclosure. It mentions that the tool reports version and variant 'when recognizable' and implies acceptance/rejection, but does not specify the return format, accepted UUID string forms, or edge cases like nil UUIDs. This is adequate but leaves room for ambiguity.

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 front-loaded with the primary purpose and uses a clear bulleted structure for usage guidance. Every sentence adds value, and there is no redundant or empty phrasing.

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 simple one-parameter tool with no output schema, the description covers purpose, usage, and exclusions comprehensively. The only notable gap is the lack of explicit return-value structure (e.g., whether it returns a boolean or an object with version/variant), which the agent would need to discover. Overall, it is nearly complete.

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 provides 100% coverage with a description for the single 'value' parameter ('UUID candidate string'). The description adds minimal new meaning beyond this, only implying the input is a string and its purpose. Since schema coverage is high, the baseline of 3 is appropriate.

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 clearly states the tool checks whether a string is a well-formed UUID and reports its version and variant. This specific verb+resource combination distinguishes it from siblings like isbn_validate and json_validate, which are explicitly called out.

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 includes explicit 'Use when' and 'Do not use when' sections, listing concrete scenarios (e.g., validating a UUID before using it as a primary key) and naming alternative tools (isbn_validate, json_validate). This fully guides the agent on when to select this tool versus alternatives.

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