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

Annotations already declare readOnly, idempotent, open-world and non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond that: the pricing model (free within the daily allowance, then $0.001 USDC per call via x402), which affects whether an agent should batch or cache calls.

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 sentences with zero filler: the first front-loads what is returned, the second carries the cost model. Nothing could be removed without losing information.

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?

An output schema exists so return values need no explanation, and annotations cover the safety profile, leaving little for the description to carry. The main residual gap is not telling the agent how to obtain a valid MSOA code (e.g. via uk-geography__search).

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 a single parameter at 100% schema description coverage, the schema already documents the required 'code' field as an ONS MSOA code. The description's phrase 'for a 2021 Middle Layer Super Output Area' lightly reinforces the vintage of the code but adds no new syntax or format guidance.

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?

Names the resource (2021 Middle Layer Super Output Area) and states the specific outputs (wards and local authority) for a given ONS MSOA code, so the agent can tell it is an upward hierarchy lookup. It does not explicitly distinguish itself from its closest sibling, uk-geography__lsoa, which is the same shape of tool at a different granularity.

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?

There is no guidance on when to use this versus uk-geography__lsoa, uk-geography__ward, or uk-geography__search, nor where the required MSOA code comes from. The only usage-adjacent note is pricing, which does not help tool selection.

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