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

readOnlyHint=true already tells the agent this is a safe, non-mutating read, so the bar is lower. The description usefully discloses the determining factors (EPC rating, council tax band, tenure, income band), but does not say the result is an indicative eligibility assessment rather than a confirmed award, nor address anything about rate limits or data freshness.

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?

A single front-loaded sentence with no padding. It is a noun fragment rather than a verb-led statement, but every word contributes to identifying the resource and its determinants.

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 zero-required-param, read-only lookup with no output schema, the definition covers what the tool returns and what eligibility depends on. It omits how to interpret results (indicative vs. confirmed), the property_id-vs-postcode preference, and any country-scoping behavior, leaving gaps an agent would hit in practice.

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 only 40% (postcode and property_id documented), so the description should compensate — yet it lists 'tenure and income band' (real params) alongside 'EPC rating and council tax band,' which are not parameters at all. That mismatch risks confusing the agent about what to supply, and it never explains the country enum or the relationship between property_id and the EPC-derived inputs.

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 the specific resource — energy-efficiency and home-improvement grant schemes — and frames it as an eligibility lookup, which separates it from the data-lookup siblings (flood, broadband, price history). It lacks an explicit verb and never contrasts itself with a sibling, but the resource is unambiguous.

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?

There is no when-to-use instruction, no prerequisites, and no mention of alternatives among the ten sibling tools. The phrase 'based on EPC rating, council tax band, tenure and income band' hints at inputs but does not tell the agent when this tool is the right call.

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