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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely new behavior: unspecified agent fee, repairs and voids fall back to standard assumptions, which are surfaced in assumptions_applied, and the tool returns a link that reopens the same deal in the calculator. This is useful beyond the structured hints, though it does not cover rate limits or failure modes.

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 dense sentence that front-loads the resource and then lists outputs, plus a short second sentence on assumptions and the return link. Every clause carries information (yield types, tax, cashflow, stress scenarios), though the output enumeration is long enough to test readability.

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 16 parameters, no output schema and only safety annotations, the description usefully compensates by enumerating what the analysis returns (deal score, break-even rate, stress scenarios) and by explaining how missing inputs are handled. A note on the units/scale of the score or the link's expiry would make it fully self-sufficient.

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%, so the schema already documents all 16 parameters, their defaults and enums. The description only restates the default-assumption behavior for agent fee, repairs and voids, adding marginal meaning beyond the schema. Baseline 3 is appropriate when the schema does 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?

States a specific verb and resource ('Full UK buy-to-let analysis for a purchase price and monthly rent') and enumerates the outputs (yields, Section 24 tax, cashflow, deal score, stress scenarios). An agent can tell it is a comprehensive single-deal analysis. However, it never names the sibling it is not, so the boundary against calculate_section_24_tax, calculate_btl_mortgage or check_deal is left implicit.

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?

Usage is only implied: the breadth of outputs signals 'use this when you want an end-to-end deal view'. There is no explicit when-to-use or when-not-to-use, and no routing guidance toward the narrower sibling calculators that cover single components (Section 24, mortgage, capital gains).

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