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

Against annotations that only cover the safety profile (readOnly, idempotent, non-destructive), the description adds substantial behavior: MEES is a legal bar not a valuation note, band letters are ranges not points, a null gap means unknown rather than 'already at potential', recommended_measures returns not_available (gap G3), and no monetary uplift figure is estimated. It also states cost (5 credits) and jurisdiction (UK only).

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 long but front-loads the core scope before the caveats, and each section (MEES semantics, band-range, missing measures, cost/keying) earns its place given the unusual semantics an agent could get wrong. Capitalized warnings aid scanning, though it could be trimmed slightly.

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 structure need not be explained, and the description instead supplies the interpretive context an agent cannot get from fields alone: how to read bands, nulls, MEES as legal constraint, and the known missing measure list. Nothing needed to call it correctly is absent.

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% — the single 'uprn' integer parameter is entirely undocumented in the schema. The description compensates by stating the tool is 'keyed on a UPRN, not an address' and telling the agent how to obtain one via address_autocomplete/address_resolve. Minor gap: it doesn't state the expected format (e.g. 12-digit) beyond the type.

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 (one property's energy rating) and enumerates exactly what it returns: current rating vs certificate potential, letter bands, assessor-recorded fabric/heating, and MEES. It implicitly separates itself from siblings like energy_profile or epc_certificates, but never explicitly names a sibling it is not, so an agent still has to infer the boundary.

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?

Strong operational routing is given: 'UK only. Costs 5 credits. Keyed on a UPRN, not an address: call address_autocomplete (free) to narrow, then address_resolve to get one.' This tells the agent the prerequisites and the exact sibling chain to use first. It stops short of stating when to prefer this over energy_profile or retrofit_candidates.

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