lookup_hsn_code

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

The annotations already mark the tool read-only and idempotent, and the description adds useful behavioral context: it returns a standard envelope with exact matches or top 5 keyword matches, uses static master data, and notes GST applicability can vary. It leaves the exact envelope shape undefined, but an output schema is present.

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 compact, front-loaded with the main operation, and organized into Args, Returns, and Notes. Every sentence adds useful information, and there is no redundant filler.

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 lookup tool, the description covers the triggering use case, both parameters, return behavior, and an important GST caveat. The only real gap is that both parameters are optional and the description does not state what happens when both or neither are provided.

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 description maps the two parameters to exact-code lookup and keyword search, and it adds concrete details such as valid code lengths and the top-5 match behavior. This goes beyond the schema, which only says 'HSN/SAC code (2-8 digits)' and 'keyword for description search'.

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 is a lookup for HSN/SAC codes by exact code or by description keyword. It names the resource and the operation, and the GST classification context distinguishes it from the many validation and calculation siblings.

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?

'Use for GST classification workflows where users provide a code or only a product keyword' gives a clear, actionable condition for when to invoke the tool. It does not explicitly list alternative tools to avoid, but the context is clear enough to route an agent.

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