Look up PIN code

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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=true, so safety and repeatability are covered without description help. The description adds useful context by naming the returned fields (district, state and post offices), which partially compensates for the absence of an output schema. It does not mention lookup failure behavior for invalid PIN codes or response format details.

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?

A single sentence with zero filler, front-loading the resource and output fields. Every clause earns its place and nothing is redundant with the schema.

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 one-parameter read-only lookup, the definition covers purpose, input format and expected return fields. With no output schema, stating what is returned is valuable and largely sufficient, though error behavior for invalid PIN codes remains unspecified.

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% with a single well-described parameter ('6-digit PIN code, e.g. 110001'), so the schema carries the full burden. The description's 'Indian 6-digit PIN code' reinforces the format and country constraint, which is marginally additive but not meaningfully beyond the schema.

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 (Find) and resource (district, state, post offices for an Indian 6-digit PIN code), so the agent immediately knows the input and output shape. It does not explicitly differentiate itself from siblings, but they cover unrelated identifiers (GSTIN, HSN, IFSC), so no real ambiguity exists.

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 'Indian 6-digit PIN code' phrasing implicitly scopes the tool to Indian postal codes, which functions as light usage guidance. There is no explicit statement of when to use this versus an alternative or what prerequisites apply, but the domain is narrow enough that no reasonable alternative exists among siblings.

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