ons_data_get_observation

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, covering the safety profile. The description adds only 'live' and 'single observation,' with no detail about failure modes, exact-match semantics, rate limits, or response behavior; 'live' also overlaps with openWorldHint.

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 single sentence is front-loaded, specific, and free of filler, making it easy to scan. However, its brevity is achieved by dropping important routing and parameter context, so it is concise but not optimally sized for the tool's complexity.

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?

The description is too sparse to fully support invocation: an agent cannot determine how to fill required dataset/edition/version parameters or know when to prefer this over siblings like ons_data_query. The presence of an output schema mitigates the return-value gap but does not compensate for the missing parameter and routing context.

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?

With 7 parameters and 0% schema description coverage, the description must compensate for the schema's silence. It names geography, measure, and time, but says nothing about dataset, edition, version, or value formats, leaving three of six required parameters completely unexplained.

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 uses a specific verb ('Fetch'), identifies the resource ('a single observation'), and names the source API ('live ONS API'). The word 'single' helps differentiate it from broader ONS query tools like ons_data_query, though it omits the required dataset/edition/version dimensions.

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 when-to-use or when-not-to-use guidance is provided, and no sibling alternatives are named. The 'single observation' phrasing only implies an exact-lookup use case, leaving the agent to infer how this differs from ons_data_query or ons_data_create_filter.

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