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

Beyond the annotations (which already cover readOnly/idempotent/destructive), it discloses two things the structured fields cannot: that the tool is gated behind a premium license, and that it never raises a protocol error but returns an {"error": ...} object. It also frames retry safety as actionable advice after correcting input, which is more than restating idempotentHint.

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?

The scoping sentence and exclusions are front-loaded, followed by the example and then the error contract. The sample output's "verdict": "..." is slightly vague, but no sentence is wasted and each block serves a distinct purpose.

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?

It goes past requirements by sketching the return shape (schedule, latest_safe_start, slack_business_days_from_today, verdict) even though an output schema exists, and it covers the error path. A minor gap: it does not explain what happens when more than 30 tasks are supplied, which the schema mentions but the description never confirms.

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; the worked input example {"due_date": "2026-06-01", "tasks": [{"name": "Draft", "days": 3}]} concretely demonstrates the nested task shape and date format. It goes somewhat beyond the schema but does not explain buffer_days or holidays interaction with the computation.

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 - planning a task schedule backward from a hard deadline in business days - and contrasts it against the sibling tools business_days and sla_due by name. An agent can distinguish it from every sibling without opening a schema.

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?

Explicit positive condition ('Use when the end date is fixed and steps must be placed backward from it') plus two explicit exclusions routing to business_days and sla_due. Nothing about tool selection is left to inference.

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