nearest_postcode

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

No annotations exist, so description must cover behavior. It mentions returning 'full enrichment data' and 'risk and demographic signals', which is good. However, it doesn't explain what happens if no postcode is found, radius effects, or coordinate validity. Adequate but has gaps.

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 short sentences, front-loaded with action and purpose. Every word earns its place; no redundancy.

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?

Despite no output schema or annotations, the description explains what it does, when to use it, and what it returns (enrichment data). Could mention radius or error states, but overall sufficient for a simple geospatial tool.

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 description coverage is 100% (all parameters have descriptions in the schema). The tool description adds no further parameter guidance beyond reinforcing 'latitude/longitude coordinate'. Baseline 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 finds the nearest UK postcode to given coordinates and returns enrichment data. It distinguishes from siblings: lookup_postcode retrieves by code, postcodes_within returns multiple, while this tool finds the single nearest from a coordinate.

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 provides a clear use case ('when you have coordinates and need the corresponding postcode'). It implies when to use but does not explicitly mention when not to or compare with postcodes_within.

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