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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is known. The description adds valuable context: it is free (no credits deducted), returns lifetime stats, and clarifies the exact structure of the response. This goes beyond 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?

The description is three sentences plus a compact return schema. Every sentence serves a purpose: action/resource, usage guidance, and cost/free note. No redundancy or fluff.

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 read-only status tool with no parameters, the description is comprehensive. It includes the return shape, usage context, and cost implications. There is no output schema, so the description carries the full burden, and it does so effectively.

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, and the schema coverage is trivially 100%. The baseline for 0 params is 4. The description does not need to explain parameters, but it effectively describes the output structure, which is the only meaningful semantic content here.

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 uses a specific verb and resource: 'Read your own PingShield config and lifetime stats.' It clearly distinguishes from sibling tools (check, subscribe, update) by focusing on status and configuration. The expected return structure is explicitly outlined.

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 states when to use the tool: 'Use to monitor your inbox protection and tune thresholds based on real traffic.' It provides clear context but does not explicitly mention alternatives or when not to use it, though sibling names imply the distinction.

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