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

Beyond the annotations (readOnlyHint=false, destructiveHint=false), the description discloses the mutation's shape: exactly ONE Adjustment, signed as settled − earned, always current-period never backdated, append-only and idempotent. It also states the dry-run default and an auth prerequisite (connected Aurgus account), which annotations do not cover. Nothing here contradicts the non-destructive hint, since the write is an append-only adjustment.

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 core action and effect, then the sign convention, then the dry-run workflow. It is dense and occasionally repetitive ("Always current-period, never backdated" restates the period point), but nearly every sentence carries operational 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?

With no output schema, the description still characterizes what the agent will see (the exact Adjustment and before/after on a dry-run) and what the result means (open balance nets to $0). Given only two parameters and a non-destructive write annotation, this leaves no meaningful gap for correct invocation.

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 value beyond the schema: it explains that a bare call dry-runs and shows the exact Adjustment plus before/after state, which the schema's terse confirm description does not convey. It also reinforces that agreement_id is mandatory via "Needs the agreement_id."

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?

The description states a specific verb and resource ("True-up an agreement") and immediately pins down the mechanic: it matches the accrual account to what was actually settled by posting one signed Adjustment. It distinguishes itself from neighbors like settle and close_agreement by explicitly noting that close-out runs this true-up as its first step.

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?

Timing is explicit ("AFTER a settlement"), the alternative path is spelled out (call without confirm to dry-run, then with confirm:true to apply), and the relationship to close_agreement is named. An agent knows exactly when this tool applies and when to reach for the sibling instead.

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