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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's job is to add behavior beyond that, and it does: it lists the return payload (rent steps, totals, expiration date, calculation trace), states the tool is deterministic, and instructs the agent to surface warnings. It does not mention rounding behavior or the potentially long monthly table, but those are documented in the schema.

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?

Three sentences, each doing distinct work: inputs, outputs, then determinism/citation guidance. The most operationally important instruction (don't do the math yourself; cite the formula) is placed last but is short and unambiguous, and there is no filler.

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 compensates by summarizing the return payload and noting warnings and a calculation trace. Combined with a fully documented 8-parameter schema and safety annotations, an agent has enough to call it correctly; only minor gaps (rounding defaults, monthly-table size implications) remain and those are covered in the schema.

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 the escalation oneOf variants, abated_months indexing, and rounding flag is already fully documented in the schema. The description only restates the parameter names in prose without adding constraints, units, or edge cases beyond what the schema provides, which is the baseline for high coverage.

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 ('Build a base-rent schedule') and enumerates the exact inputs that drive it (commencement date, term, area, starting $/SF, escalations, abated months). It is clearly a rent-schedule generator, but it never names the closest siblings (calc_net_effective_rent, calc_lease_remeasurement_asc842, calc_percentage_rent) to draw the boundary.

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 on when to reach for the tool, which is meaningful guidance for an agent that might otherwise compute rent in-head. It stops short of exclusions or routing rules (e.g. when to use calc_net_effective_rent instead), so it is clear context without alternatives.

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