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

With no annotations provided, the description carries the burden of behavioral disclosure. It states the tool is 'offline', which is useful context implying no network call and likely deterministic behavior. However, it does not disclose what the output looks like (e.g., boolean true/false, pass/fail string), whether it accepts partial input, or how it handles invalid characters. The 'offline' note adds some value but the behavioral detail is thin.

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, compact sentence that front-loads the tool's purpose ('Luhn Check') and adds the key qualifier ('offline'). It is appropriately sized for a simple validation tool and contains no filler. It loses one point because it could have used the available space to clarify the input format or output without becoming verbose.

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 single-parameter validation tool, the description is nearly adequate: it names the algorithm, the target formats, and the offline nature. However, the complete absence of parameter semantics and output format details leaves an agent guessing about acceptable input formatting and return values. The output schema exists but is not shown in the provided context, so the description should have covered the return shape.

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?

Schema description coverage is 0%, and the only parameter 'q' has no description beyond its type and default. The tool description does not explain what 'q' should contain (e.g., a raw number, spaces allowed, with or without dashes). The name 'q' is generic and the description's mention of 'card/IMEI' is the only hint. The description fails to compensate for the schema's lack of parameter documentation.

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 states a specific verb ('Validate') and resource ('card/IMEI Luhn checksum'), and notes it works offline. It clearly distinguishes the tool's purpose from siblings like 'checksum', 'creditcard', 'imei', and 'hashid' by naming the exact algorithm and use case. It could be slightly clearer about what input format is expected, but the core purpose is unambiguous.

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 implies when to use it: when you need to validate a Luhn checksum for a card or IMEI offline. However, it does not explicitly state when not to use it or mention alternatives like 'checksum' or 'creditcard' for related but different tasks. The context is clear enough for an agent to select it for Luhn validation, but there is no explicit routing guidance.

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