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

No annotations are provided, so the description carries the full burden. It proactively discloses the stateless nature ('records no decision and leaves no dashboard timeline trace'), which is a meaningful behavioral trait. It also mentions what the tool returns (state code lookup), though return format details are lacking.

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?

Two sentences, no fluff. The primary purpose is front-loaded, and every sentence contributes value (what it validates, what it returns, and its statelessness).

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?

Given the simple tool (one param, no output schema, no annotations), the description adequately covers the core behavior, including the stateless side-effect. It leaves some ambiguity about the exact return format, but the overall purpose is clear.

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 0% and there is only one parameter, 'gstin'. The description says 'Validate a GSTIN format', which tells the user to pass a GSTIN string, but does not provide format examples or constraints. The parameter name is self-explanatory, so this is borderline adequate.

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 clearly states the tool validates a GSTIN and specifically mentions the mod-36 check digit and state code lookup. This is a specific verb+resource combination that distinguishes it from sibling validators for other identifiers (e.g., cpf_validate, iban_validate, sin_validate).

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 the tool is used when one needs to validate a GSTIN and mentions stateless behavior, providing clear context. It does not explicitly mention alternatives or when-not-to-use, but the specific naming and purpose make the intended usage clear.

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