lookup_pincode

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

Beyond the annotations (readOnlyHint=true, idempotentHint=true), the description adds meaningful behavioral details: input normalization of spaces/hyphens, the fact that one pincode may map to multiple post offices and all are returned, and the standard envelope with location hierarchy. This gives an agent clear expectations about behavior and edge cases.

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 and well-organized with a summary, use-cases, Args, Returns, and Notes sections. Every sentence earns its place with no redundancy or 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 single-parameter read-only lookup with an output schema present, the definition covers the essential context: purpose, when to use, input formatting, output envelope shape, and cardinality notes. Nothing an agent needs to call it correctly is missing.

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 schema already covers the parameter with 100% description coverage, providing the baseline of 3. The description adds value by detailing that spaces/hyphens are accepted and normalized and confirming the 6-digit format, which is useful semantic detail beyond the schema's simple '6-digit pincode'.

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 opens with a specific verb and resource: 'Look up India pincode details and return all post offices for that code.' This clearly differentiates it from sibling lookup tools such as lookup_ifsc, lookup_bank, and lookup_hsn_code, which target different identifiers.

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 explicitly states when to use it: 'Use for address normalization, district/state extraction, and GST state crosswalk use-cases.' It does not mention exclusions or alternatives, but the use-cases are specific enough to guide selection among the sibling tools.

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