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

Annotations already declare readOnlyHint, idempotentHint and a closed world, so the safety profile is covered. The description adds value beyond that by disclosing the calculation methodology, partial first/last month handling, breakage at expiry, and an explicit limitation on multi-element/variable contracts. It does not mention rate limits or pagination, but none are relevant for a pure computation.

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?

Front-loaded with the deliverable, then the three model behaviors, then the disclaimer; every clause carries information. The 'same math as revexos.com/revenue-recognition-calculator' line is closer to promotion than guidance and slightly inflates the length.

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 naming the returned columns (billed, recognized, deferred, unbilled per month), so an agent knows what it gets back. Model-specific parameter interactions are covered, leaving only minor gaps such as term/commitment defaults for usage beyond what the schema states.

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 90%, so the baseline is 3, but the description adds genuine semantics the schema lacks: partial first/last month prorated 'by its own days', billing 'in advance', optional deposit on milestone, and breakage at expiry for usage. These rules tell the agent how parameter choices change the math, not just their names.

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 month-by-month revenue recognition schedule) and enumerates the exact output columns (billed, recognized, deferred, unbilled per month). The three named models and the ASC 606 / IFRS 15 framing clearly separate it from the invoice/AR siblings.

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?

Explains what each model means and when it applies (subscription = ratable monthly with upfront/annual/quarterly/monthly billing, milestone = recognition on delivery, usage = prepaid drawdown with overage), and adds a scope exclusion ('not a substitute for an accountant on multi-element or variable contracts'). It does not name a sibling alternative or state prerequisites, so it stops short of a 5.

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