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

Annotations already establish that this is a safe, non-writing, closed-domain read (readOnlyHint true, openWorldHint false), so the bar is lower. The description adds useful context by promising 'official sources and checked dates', which hints at provenance and freshness of the answer, but it does not state that results are advisory, may not reflect the latest HMRC/OZEV rule changes, or how stale the checked dates might be.

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 that identifies both schemes immediately, with no preamble or filler. The trailing 'official sources and checked dates' clause earns its place by signalling result provenance.

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 six-parameter tool with no output schema, the description should say more about what comes back — eligibility verdict, grant amount, relief value, or all three — since cost and sockets suggest computed monetary outcomes. It covers what the tool checks but not what the caller receives, leaving a real gap.

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 100%, with each of the six properties (org, tax, cost, in_uk, sockets, off_street) documented inline, so the schema carries the semantics. The description adds nothing about these inputs, and the baseline of 3 applies when structured fields do the heavy lifting.

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 verb (checks) and two concrete resources: the Workplace Charging Scheme grant and the 100% first-year allowance. This distinguishes it from informational siblings like area_charging_facts, charger_size and charging_time, though it never explicitly frames itself as an eligibility/entitlement check the way an agent might need.

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 guidance on when to call this vs the sibling tools or what preconditions exist (e.g. must the user already own chargepoints, must the site be in the UK). The schema implies eligibility-checking inputs but the description offers no when/when-not routing.

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