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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the safety profile is covered. The description adds genuinely useful non-schema context: the free daily allowance and the $0.001 USDC x402 pricing after that, which matters for an agent deciding whether to call it. It omits result limits and ranking behavior.

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, zero filler, purpose front-loaded ahead of the pricing note. Nothing here is redundant with the title.

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. Purpose, covered entity types, and cost are all present; for a simple two-parameter read-only search this is complete enough to call correctly.

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 both parameters are already documented, including the 'ward (default)' enumeration for type. The description restates the same type list in prose and adds nothing about matching syntax or partial-name behavior beyond what the schema says.

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?

Clear verb+resource: 'Search ... names for their ONS codes', and it enumerates the six geography types covered. It implicitly complements the type-specific siblings (uk-geography__ward, uk-geography__county, etc.), but never names or contrasts them explicitly, so sibling differentiation is left to inference.

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 cost context (free allowance, then paid) but says nothing about when to use this search vs. the per-type lookup tools, nor about partial-match expectations. Usage is implied by 'search ... names' rather than stated as guidance.

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