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

Annotations only declare it is a non-read-only, non-destructive write; the description goes far beyond that by disclosing the full workflow: results are recorded on the engagement file, a principal signs before workpapers are delivered, and ungrounded inputs become OPEN ITEMS rather than guesses. It also states the tool is interactive (it will ask for a missing rate), which an agent needs to know before calling.

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?

Purpose is front-loaded in the first clause, followed by inputs, outputs, and edge-case handling in a logical order. It is dense and long, but nearly every clause carries operative information (citation references, exclusion rules, open-item behavior) rather than 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?

For an 11-parameter, no-output-schema tool with minimal annotations, the description supplies what is otherwise missing: it names the three computed outputs (liability, ROU asset, amortization schedule), explains the two classification paths, and clarifies how it handles ungroundable inputs. An agent has everything needed to call it correctly and to anticipate the response shape.

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%, so the baseline is 3, but the description adds genuine meaning by linking parameters to the accounting model — ROU asset = liability + initial direct costs − incentives, and usage-based variable payments excluded from the liability under 842-10-30-6. The 'never assumes a rate' note on the discount rate is a real semantic constraint beyond the schema text.

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 — measure a lease under ASC 842 — and immediately scopes it to the lessee side for real estate and equipment. This is unmistakably distinct from siblings like compute_revenue_contract, compute_commission, or compute_close, which cover different accounting domains.

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?

Gives clear preconditions (term, CERTIFIED discount rate, payment schedule) and an explicit exclusion (lessor accounting deferred to v2), plus the behavioral rule that a missing rate triggers a question rather than an assumption. It stops short of naming a sibling alternative for adjacent tasks, but the scope boundaries are unambiguous.

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