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

The annotations already cover read-only, idempotent, non-destructive, and open-world behavior. The description adds a useful behavioral trait that the annotations do not: the pricing model, including the free daily allowance and $0.001 USDC per call via x402.

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 two efficient sentences with no wasted words. It front-loads what the tool returns and follows with the cost model, both of which are relevant to calling the tool.

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?

For a one-parameter lookup with a complete output schema and rich annotations, the description is nearly complete: it states the return relationship and pricing. Minor gaps remain around error behavior for unknown codes, but the output schema covers return values.

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 100%, so the single parameter is fully documented in the schema as an ONS LSOA code. The description does not add syntax, format, or validation details beyond what the schema already provides, which matches the baseline for high-coverage schemas.

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 names a specific resource and version (2021 Lower Layer Super Output Area) and states what it returns (ward and local authority). It is clearly a lookup tool, but it does not explicitly distinguish itself from siblings such as msoa, ward, or local-authority.

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 gives no guidance on when to use this tool versus alternatives. It does not mention that the caller should have an LSOA code or when to prefer msoa, ward, or other geography lookups.

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