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

Annotations already declare readOnlyHint=true, so the agent knows this is a safe read operation. The description adds only that it reports the version of the service, which is a mild extension. It doesn't mention what the return value looks like or any edge cases, but for a simple getter with annotations covering safety, this is acceptable.

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 a single, front-loaded sentence with zero wasted words. It states exactly what the tool does and nothing more, which is ideal for this trivial utility.

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?

With an output schema present, the description need not explain return values. For a zero-parameter, read-only version check, the description is fully sufficient. No additional context is required.

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 are zero parameters, so the description need not add any parameter semantics. With schema coverage at 100% (vacuously true), the baseline for 0 parameters is 4. The description doesn't need to explain anything further.

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 'Report the version of this MCP service' uses a specific verb ('report') and resource ('version'), and clearly distinguishes itself from all sibling tools, none of which deal with versioning. An agent immediately understands what this tool does without needing to open the schema.

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?

There are no alternative tools for version retrieval among the 40+ siblings, so explicit when/when-not guidance is unnecessary. The description clearly implies its use case: checking the service version. While it doesn't state 'use when you need version info', the context makes it obvious.

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