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

Annotations already declare readOnlyHint=true, idempotentHint=true, non-destructive and closed-world, so the safety profile is covered. The description adds real context beyond that: the tool is deterministic, it returns intermediate steps and warnings, and outputs should be cited with formula id calc.walt@1 — useful attribution behavior an agent would not otherwise know. It does not describe response shape or how warnings affect the result, keeping it below 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?

Two front-loaded sentences with no filler; the definition of the metric comes first and the operational instruction second. The second sentence is dense with citation and warning clauses, but every clause carries actionable information.

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 read-only calculator with no output schema and fully documented parameters, the description covers purpose, determinism, and post-call obligations (cite the formula, surface warnings). Minor gaps remain around edge cases such as expired leases or zero-weight portfolios, but an agent has enough to invoke it correctly.

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% and the schema already documents as_of, weight_by, and the per-lease fields including the conditional requirements (area_sf when weight_by=area, annual_rent when weight_by=rent). The description restates the weighting choice without adding format, default behavior, or edge-case rules, so the baseline 3 applies.

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 precise computed quantity with its unit ("weighted average remaining lease term in years"), the two weighting options, and the as-of basis, so an agent can immediately tell this apart from the other calc_* tools such as calc_rent_schedule or calc_net_effective_rent. It stops short of naming any sibling explicitly, which keeps it from 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?

"use this instead of doing the math yourself" gives an explicit selection rule: any WALT request should route here rather than to ad-hoc arithmetic. There are no when-not conditions or exclusion cases (e.g. single-lease portfolios, all leases already expired), so the guidance is clear but not exhaustive.

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