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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety is covered. The description adds genuinely new behavioral context: the computation is deterministic, it returns warnings that must be surfaced, and outputs include a citation token calc.renew_vs_relocate@2 plus intermediate steps. It does not discuss failure modes or validation errors, which keeps it short of a 5.

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 purpose and output set are front-loaded in the first sentence, with the operational instructions (cite formula, surface warnings) in a short second sentence. The long parenthetical cost enumeration is informative but dense; overall there is little 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 nested five-parameter comparison tool with no output schema, the description compensates by naming each returned figure and flagging that warnings and steps are returned. The main gap is that it does not clarify that both cases run over horizon_months or how allows offset costs is handled in the results, though the schema carries that.

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 every parameter including nested schedule and escalation variants is already documented in the schema; baseline 3 applies. The description's parenthetical cost list (TI net of allowance, moving, downtime, double rent, termination, disruption) lightly mirrors the relocate parameters and confirms the offset behavior for allowances, but adds no syntax or format detail beyond the schema.

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?

"Compare renewing in place with moving over one horizon" gives a specific verb and decision resource, and enumerates the outputs (NPV, discounted effective rent, break-even starting rent, year-by-year cash flows). It is clearly distinguishable from siblings like calc_net_effective_rent, calc_rent_schedule, and calc_lease_vs_own, which compute single-case metrics rather than a two-scenario comparison.

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?

"Deterministic: use this instead of doing the math yourself" gives an explicit directive and distinguishes it from manual calculation. However, it does not name the sibling alternatives (e.g. calc_rent_schedule for one-case schedules, calc_npv for generic discounting) or state when this tool is not appropriate, so routing is good but not exhaustive.

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