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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds valuable context beyond this: the data source, coverage timeframe, no-auth requirement, and Open Government Licence. It also discloses the fields returned. This goes beyond the annotations without contradicting 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 two sentences, front-loaded with the core action and scope, followed by a compact enumeration of filters and return fields. Every phrase adds information and nothing is redundant with the schema or annotations.

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 output schema, rich annotations, and complete parameter descriptions, the tool definition is fully self-sufficient. The description covers data source, geographic and temporal scope, filters, return fields, authentication, and licensing. An agent has everything needed to invoke it 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?

The input schema has 100% description coverage for all 7 parameters, so the schema already documents each parameter's meaning and constraints. The description summarizes the filter categories (price, date, pagination) but does not add any meaning beyond the schema. Baseline 3 is appropriate.

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 opens with a specific verb ('Search') and a precise resource ('HM Land Registry Price Paid Data'), then scopes it to 'every residential property sale in England & Wales since 1995' and 'exact UK postcode.' This clearly distinguishes it from the sibling by_area tool through the explicit postcode-scoping language.

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 clearly conveys when to use this tool: when searching by exact UK postcode. It lists optional filters, implying scenarios like filtering by price or date. However, it does not explicitly name alternatives (e.g., by_area) or state when not to use it, so it stops short of a full 5.

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