part_s_ev

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

With no annotations, the description carries the burden of behavioral disclosure. It discloses that results are 'Indicative', details return values (required charge points, cable routes, minimum power, cost caps), and includes the specific '1-in-5 for non-residential' rule. This gives the agent a realistic expectation of outputs, but it could be more explicit about whether the tool requires any special permissions or has other side effects (though as a calculator, these are minimal).

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 two sentences, front-loaded with the tool's purpose and scope, and every sentence adds value. It efficiently packs in applicable regulations, use cases, outputs, and a key calculation rule without waste.

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 calculator with no output schema and no annotations, the description does state what it returns and the key 1-in-5 rule. However, it lacks guidance on how required vs optional parameters should be combined (e.g., 'provide dwellings for residential, covered_car_park for non-residential'), which could lead to incomplete or incorrect invocations.

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?

The schema covers 60% of parameters with descriptions (dwellings, parking_spaces, covered_car_park), and the description adds context about building types and works types, plus the '1-in-5' rule for cable routes. However, it does not clarify the conditional relationship between building_type and parameters like dwellings or covered_car_park, leaving some ambiguity for the agent.

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 clearly states the tool is a 'UK Approved Document S 2021 electric-vehicle charge-point requirement calculator' and specifies the scope (new build, major renovation, residential, non-residential). It also lists concrete outputs (charge points, cable routes, minimum power, cost caps), distinguishing it from sibling tools like generic carbon calculators or building readiness checkers.

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?

The description explicitly defines the applicable scenarios ('new build and major renovation, residential and non-residential'), providing clear context for when to use the tool. It does not, however, mention exclusions or direct comparisons to alternative tools, so it stops short of a full 5.

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