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

With no annotations, the description carries the behavioral burden and mostly meets it: it states the tool returns explanatory content and specifies what that content covers (recipients, consent wording, confirmation method). It does not explicitly say 'this tool itself has no side effects' or 'does not submit an enquiry,' but the verbs 'States' and 'returns' strongly signal a read-only informational tool.

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 short, front-loaded with 'Read first,' and every clause contributes meaning. The 'Also returns' sentence is slightly ambiguous about its subject, and the title duplicates some of the body's content, but overall the structure is efficient.

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-input, no-output-schema explainer tool, the description is nearly complete: it names the product context, the sibling it explains, and the topics its output covers. It could more explicitly declare that this tool itself does not create or submit anything, but that is strongly implied by the framing.

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 tool has zero parameters and the schema is already fully covering that (an empty schema), so there are no parameter semantics to add. The description adds useful non-schema context about what the returned explanation contains, which is the relevant semantic value here.

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 uses a specific verb ('States') against a specific resource ('what submit_enquiry does on HMO Mortgage Calculator') and then concretely defines that scope: it starts an enquiry with human providers, not a purchase or guaranteed quote. This clearly separates it from submit_enquiry (the action itself) and from other describe/calculation siblings.

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 opening 'Read first' explicitly instructs when to use this tool — before relying on or acting through submit_enquiry. It identifies the target sibling and the intended context, though it does not explicitly compare against calculator_describe or enquiry_fields.

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