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

Annotations already declare readOnlyHint=true, and the description reinforces a non-destructive read operation. It adds value by detailing the exact data returned (tool call counts, success rates, average latency), exceeding what annotations provide.

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?

Single, concise sentence that front-loads the purpose and lists key output fields. No redundant or irrelevant information; every word earns its place.

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 zero-parameter tool with readOnlyHint annotation, the description completely covers the purpose and return values. No output schema exists, but the description adequately explains what the tool returns.

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 has zero parameters, so schema coverage is 100%. Description does not need to explain parameters but provides no additional semantic info. Given the absence of parameters, the baseline expectation is met.

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?

Description clearly states the tool retrieves usage statistics for the MCP server session, listing specific metrics (tool call counts, success rates, average latency). The verb 'Get' and resource 'usage statistics' are specific and distinguish it from sibling tools, none of which provide similar stats.

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?

Usage is implied as a monitoring/information tool, but there is no explicit guidance on when to use it vs alternatives, nor any 'when not to use' instructions. The description lacks context for optimal invocation.

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