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

Annotations already cover the read-only/idempotent safety profile, and the description adds substantial extra context: the coverage constraint (~1/4 price, ~1/5 yield), the instruction to read meta.coverage so thin results read as thin, and the observation that most auctioneers publish only a guide. That is exactly the behavioural disclosure annotations cannot carry.

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?

Front-loaded with the resource and payload, then unique value, use cases, alternatives, coverage caveat, and parameters. Each section earns its place, though the coverage paragraph is somewhat verbose and the whole definition runs long for a listing endpoint.

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?

For a complex 11-parameter tool with no annotation gaps and an output schema present, the description supplies what the schema cannot: the enum values, the coverage caveat with meta.coverage guidance, and the sibling routing. An agent has enough to call it correctly on the first attempt.

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 0%, so the description must compensate. It documents the high-value filters well: with_achieved_price, with_yield, and the actual auctioneer enum values (schema only declares an untyped string), plus ISO date format. It leaves limit, offset, sold_only, is_commercial, postcode_area and postcode_district unexplained, so several of the 11 parameters remain opaque.

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 resource (individual UK auction lots) and enumerates the payload fields: guide price, sold status, hammer price, net yield. It also distinguishes the dataset from listings portals and from asking-price/private-treaty siblings, so an agent can tell it apart from auction_comps, property_history, or market_volume_series.

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?

Gives explicit use cases (achieved outcomes, guide-price realism, yields, district auction behaviour) and an explicit when-not with named alternatives: 'For asking-price or private-treaty sales use market_volume_series or property_history instead'. It also tells the agent to route yield questions to the acuitus auctioneer.

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