sg_postal_lookup

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

No annotations are provided, so the description must convey behavioral traits. It states the tool is free and covers all districts, which adds context, but it does not disclose any limitations, rate limits, authentication needs, or potential errors. For a simple lookup, this is adequate but could be more transparent.

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 extremely concise: two sentences that front-load the core action and outputs. Every word contributes to understanding, with no redundancy. It efficiently conveys purpose, scope, and cost.

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 tool's simplicity (one parameter, no output schema) and the context signals (100% schema coverage, no nested objects), the description is complete. It specifies what information is returned (district number, name, area names) and that it covers all 28 districts. No additional details are necessary for correct usage.

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 input schema already describes the parameter 'postal_code' with format details (6 digits, example). The description does not add additional meaning beyond what the schema provides. With 100% schema coverage, a baseline score of 3 is appropriate.

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's purpose: 'Look up Singapore postal code to find the district number, district name, and area names.' It uses a specific verb ('look up') and resource ('postal code'), and the mention of covering all 28 districts distinguishes it from sibling tools that focus on HDB, property, or MRT data.

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 explains the tool's scope ('Covers all 28 postal districts') and notes it is free, but does not explicitly state when to use this tool over alternatives or provide exclusion criteria. While the sibling tools are distinctly different, the lack of direct usage guidance makes this dimension adequate but not strong.

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