lookup_postcode

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

No annotations provided; the description indicates a read-only lookup returning details. It does not explicitly state non-destructive behavior or any potential rate limits, but the simple nature of the tool makes it adequate.

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 very concise: one sentence plus a clear args list. It is front-loaded with the core purpose and efficiently uses every word without 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?

Given the low complexity (single parameter), presence of an output schema, and specific return fields listed, the description is mostly complete. It could mention handling of invalid postcodes but is sufficient for typical use.

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 parameter 'postcode' is described with an example format (e.g., SW1A 1AA), adding meaning beyond the schema's type string. Schema coverage is 0%, and the description compensates well with format and example.

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 'Look up details for a UK postcode', specifying the verb 'look up' and the resource 'postcode'. It distinguishes from sibling tools like get_crime_by_postcode or find_mp, which have different purposes.

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?

No explicit guidance on when to use this tool versus alternatives like nearest_postcodes or find_mp. The usage context is implied by the description but lacks exclusions or alternative suggestions.

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