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

Annotations already declare a safe, idempotent read, but the description adds substantial context they do not carry: the input is echoed back nowhere, inputs are neither stored nor logged, and a pass proves only checksum validity, not registration or ownership. This is exactly the privacy/limit disclosure an agent needs for handling personal data.

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?

Front-loaded with what it does, then limits and privacy in order of importance; every sentence is functional. The two consecutive caveats about existence and ownership restate the same idea, which is defensible emphasis but slightly redundant.

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?

Covers the three things an agent needs for this tool: what is validated, what a pass does not imply, and how the sensitive input is handled. An output schema is present, so return shape need not be restated.

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 coverage is 100% and there is only one parameter, so the baseline would be 3. However the description adds a real constraint the schema omits: the value must be 11 digits, while the schema merely sets maxLength 64. That closes a genuine gap the structured field leaves open.

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?

States a specific verb and resource (validates the check digits of an 11-digit TCKN) and scopes it precisely to format/checksum rather than existence. The note that individuals also use this number as their tax number hints at the boundary with validate_tax_number, so an agent can distinguish it from siblings without opening 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?

Clear about the context in which the tool applies (pure format/checksum validation of a Turkish ID) and explicitly warns what a positive result does NOT mean. It stops short of explicitly routing between siblings — e.g. 'use validate_tax_number for corporate VKN' — so it lacks the explicit alternative-selection guidance of a 5.

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