postcodes_within

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

No annotations exist, so the description carries the full burden. It discloses ordering (distance ascending), cost (one quota per postcode), requirements (Starter plan), and max radius (5000m). Missing details on error handling or rate limits, but the disclosed info is substantial.

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 concise, consisting of four sentences that front-load the purpose, then add ordering, cost/requirements, and a size constraint. Every sentence serves a purpose with 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?

While the description covers key behaviors, it lacks details about the return format (what 'full enrichment data' contains) and does not mention pagination or limits on the number of postcodes returned. This is a gap for a tool that could return many results.

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%, but the description adds value by explaining the radius unit, default, and max, and clarifying that results are ordered by distance. It reinforces the coordinate reference (WGS84) and adds behavioral context not in 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?

The description clearly states the tool returns all UK postcodes within a radius of a lat/lon coordinate with full enrichment data. It distinguishes from sibling tools like 'nearest_postcode' which likely returns a single nearest postcode, and 'lookup_postcode' for a specific postcode.

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 clear context on when to use the tool (to get all postcodes within a radius) and includes constraints (Starter plan required, quota cost, max radius). However, it does not explicitly contrast with alternatives or state when not to use it.

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