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

Annotations already declare this a read-only, idempotent, non-destructive, closed-world computation, so the safety profile is covered. The description usefully adds the return payload (interest, arrangement fee, exit fee, total cost, effective APR, comparison), provenance ('lender-grade formulas calibrated against live UK lender pricing') and the £250k floor. It does not say these are indicative estimates rather than a binding quote, which matters for a financial 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?

Front-loaded with the verb and output list, then provenance, then eligibility, then when-to-use — a logical order. Four sentences with little waste, though the broker-branding sentence is more marketing than decision-relevant for an agent.

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?

With no output schema, the description correctly takes on the burden of naming the returned fields, and it covers eligibility and usage triggers. The only meaningful omission is guidance that results are estimates rather than offers, plus no differentiation from the sibling calculator.

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 100% and each parameter carries a detailed description with ranges, conventions and examples, so the schema does the heavy lifting. The tool description itself adds no parameter-level meaning beyond what is already structured, which caps it at the baseline-plus level.

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?

States a specific verb+resource ('Calculate the total cost of a UK bridging loan') and enumerates the three interest structures plus the outputs returned, so the agent knows exactly what the tool produces. It does not, however, differentiate itself from the sibling 'uk_bridging_loan_calculator', which sounds almost identical in scope.

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 final sentence gives explicit trigger conditions ('user asks about the cost of a bridging loan', 'rolled-up vs retained vs serviced', 'how much a specific facility will actually cost'), and the eligibility floor of £250,000 is stated. No exclusions or routing away from the near-identical sibling calculator are given, so it stops short of a 5.

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