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

Annotations already declare readOnlyHint=true and idempotentHint=true. The description adds valuable context beyond annotations by noting 'FREE with API key — no credits deducted' and by specifying the return structure with lifetime counters. No contradiction with annotations.

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 concise and front-loaded: it states the core action in the first sentence, followed by a compact return schema snippet. Every sentence adds value, including the cost note and use-case guidance. No 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 tool with no parameters and no output schema, the description is complete. It explains the tool's purpose, return fields, use case, and cost implications. The inline return structure compensates for the lack of an output schema.

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 the baseline is 4. The description doesn't need to explain parameters; it instead describes what is returned. It adds no parameter-specific meaning, but that's appropriate given there are none.

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 starts with a specific verb+resource pair: 'Read your own PingShield config and lifetime stats.' It clearly distinguishes from siblings like x711_ping_shield_check (checking specific messages) and x711_ping_shield_update (modifying config) by focusing on reading configuration and statistics.

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 a direct use case: 'Use to monitor your inbox protection and tune thresholds based on real traffic.' While it doesn't explicitly mention alternatives or exclusions, the read-only nature and the sibling tool names make the intended usage context clear.

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