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

With no annotations, the description carries the full burden. It discloses the core behavior—combining Land Registry sales and Rightmove rentals to produce a gross yield figure—but does not mention potential limitations (e.g., data availability, boundary cases, update frequency). It doesn't contradict any annotations (none exist) but also doesn't go beyond the basic method.

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: the first states the core purpose, the second adds the data sources and output. It is front-loaded, concise, and every word contributes value. No fluff or repetition.

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 tool's moderate complexity (5 params, output schema present, no annotations), the description is adequate. It explains the calculation method and output, while parameter details are covered by the schema. It could mention data coverage or error scenarios, but the core purpose is well captured.

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 coverage is 100%, so the schema already documents all 5 parameters with descriptions and defaults. The description adds no additional parameter-specific meaning beyond the schema, so a baseline score of 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 clearly states the tool's purpose: 'Calculate rental yield for a UK postcode.' It specifies the verb (calculate), the resource (rental yield), the scope (UK postcode), and the method (combines Land Registry sales data with Rightmove rental listings). This clearly distinguishes it from siblings like rental_analysis (which likely provides broader rental analysis) and ppd_transactions (which is raw sales data).

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 implies the primary use case—calculating gross yield using two specific data sources—but does not explicitly state when to choose this tool over siblings such as rental_analysis or rightmove_search. It lacks exclusions or alternative recommendations, so guidance is only implicit.

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