os_places_by_uprn

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, covering safety and side-effect expectations. The description adds no additional behavioral context (e.g., return format, possible null results). It doesn't contradict annotations, but also adds minimal value beyond them.

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 a single, front-loaded sentence with no filler. It's appropriately concise for a simple lookup tool, though it could arguably be slightly expanded without losing efficiency.

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 low complexity (one required parameter), presence of an output schema, and annotations covering safety, the description is fairly complete for its purpose. It lacks usage guidance and parameter elaboration, but the core function is clear. A longer description would be nice but not critical.

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 0%, so the description must compensate. It only mentions 'by UPRN' without explaining what a UPRN is, its format, or any constraints. The agent gets no semantic help beyond the parameter name itself, which is insufficient given zero schema descriptions.

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 'Lookup a single address by UPRN' clearly states the verb, resource, and the key identifier. It differentiates from siblings like os_places_by_postcode and os_places_search by specifying the exact lookup mechanism, so an agent can select it unambiguously.

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 no guidance on when to use this tool versus alternatives. It doesn't mention that it should be used when a UPRN is available, nor does it point to sibling tools for other lookup keys. An agent must infer usage from the tool name and context.

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