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

Annotations already cover read-only/idempotent/closed-world safety, so the description adds context beyond that bar: UK-only scope, a 20-credit cost, and a reasoned disclosure that no kWp/yield figure is returned because pitch, orientation and shading are absent from the warehouse. The rationale matters because an agent could otherwise present footprint as a forecast.

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-loads what is returned, then the exclusion and its rationale, then the operational constraints (region, cost, key type). Every sentence carries information an agent needs; there is no 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?

An output schema exists, so return values need not be described, and the description instead covers the gaps that schema cannot: scope, cost, key semantics, and the deliberate omission of generation estimates. Nothing needed to call this correctly is missing.

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 0%, so the description must carry the parameter burden, and it does the most important part: the key is a UPRN, not a free-text address, plus the route to obtain one. It does not clarify that the parameter is an array accepting multiple UPRNs, leaving minor ambiguity against the schema.

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 and enumerates exactly what is returned: footprint area, roof shape and material, building height, and panel presence. It also explicitly names what is NOT produced (a generation estimate), which separates it from siblings like energy_profile and property_energy_retrofit.

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 preconditions and a call sequence: UK-only, keyed on UPRN not address, call address_autocomplete (free) then address_resolve to obtain one. It also states the cost (20 credits) and instructs how to report the result as a screening figure, leaving nothing to inference.

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