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

Annotations already declare readOnlyHint=true, and the description adds useful behavioral context by explaining the data sources and the median-based calculation. It does not contradict annotations and provides meaningful methodology detail beyond the schema.

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 focused sentences that front-load the primary purpose and then explain the method. Every sentence earns its place with no redundancy or filler.

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 rich output schema, full parameter documentation, and readOnly annotation, the description covers the essential behavior. It could mention caveats such as data coverage limitations or that this is gross yield (not net of costs), but the existing context is sufficient for correct invocation.

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 schema fully documents all five parameters. The description adds no parameter-specific semantics beyond stating the core median sale price/median rent calculation, which is already reflected in the tool's purpose.

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 ('Gross rental yield for a UK postcode') and a specific computation combining Land Registry sale comps and Rightmove rental listings to produce a gross yield percentage. This clearly distinguishes it from sibling property tools like prop_rental_analysis or prop_property_comps.

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 usage by stating what the tool computes, so an agent can infer it should be used when a gross yield percentage for a UK postcode is needed. However, it provides no explicit when-to-use guidance, exclusions, or alternatives relative to the many sibling property tools.

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