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

With no annotations, the description carries the full burden and does substantial work: it discloses cost (free), data windows (3 years, ~800 m radius, last month), and that a paid upsell link is included in the response. It does not cover failure modes for malformed or partial postcodes, which is the remaining gap.

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, front-loaded with the 'FREE' signal, then a tight enumeration of outputs, closing with the upsell behavior. Every clause earns its place and nothing is padded.

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?

No output schema exists, so the description must cover return content, and it does list the data categories plus the included purchase link. It stops short of describing response shape or what happens when data is unavailable for a postcode, which an agent would want.

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% and the sole parameter is documented with an example format, so the schema already does the heavy lifting. The description adds nothing about postcode syntax or normalization beyond what the schema states, so baseline 3 applies.

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?

States a specific verb+resource (property snapshot for one UK postcode) and enumerates exactly what the snapshot contains: sold price, sales count, flood band, crimes, EPCs, amenities. The 'quick snapshot' vs 'full report' framing lets an agent distinguish it from postcode_report and buy_report_link without opening any schema.

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?

Usage is only implied: 'FREE' and 'Quick' versus 'the full report' signals this is the lightweight/free preview path, but the description never explicitly says when to choose postcode_report instead or when the paid path is warranted. The agent must infer the routing.

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