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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description contributes a useful scope boundary — this tool will not emit product specs or savings figures — but says nothing about what kind of response it produces (guidance text vs. structured list) or how the NSW loan list is surfaced.

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?

Two short sentences, front-loaded with the positive trigger and followed by the exclusion, with zero filler or restated field labels. Every clause constrains agent behaviour.

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-parameter, read-only knowledge tool with no output schema, this covers what the tool explains and what it refuses to do. A brief note on what a returned answer looks like would make it complete, but nothing an agent needs to invoke it correctly is missing.

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 single optional 'question' parameter is documented at 100% coverage in the schema, including the PII refusal rule, so the description carries no burden and adds nothing beyond it. The baseline of 3 applies: schema does the work, description is silent on the parameter.

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 subject domain (ceiling insulation and draught-proofing) and adds coverage scope ('including the NSW loan list'), which is far more than a restatement of the name. It does not explicitly distinguish itself from overlapping siblings such as explain_loan_basics or explain_loan_options, which also touch the loan list, so it falls short of a 5.

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?

It gives a clear positive trigger ('when explaining ceiling insulation and draught-proofing') plus explicit exclusions ('do not use this to specify a product or print a savings figure'), which implicitly routes product questions to product_faq and figures to estimate_bill_savings. It stops short of naming those siblings, leaving the agent to infer the mapping.

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