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

Annotations already declare readOnly, idempotent and non-destructive, and the description layers genuinely non-obvious behavior on top: the objective is lexicographic (fill slots, then spread hours, then preferences), solver_status is returned, errors never surface as protocol errors but as {"error": ...}, and retry after correcting input is safe. Licensing and scale limits are disclosed too.

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 core purpose and the PREMIUM flag are front-loaded, and every subsequent sentence adds new information. The inline JSON examples make it a dense single block rather than a structured section list, which costs a little scannability, but there is no wasted prose.

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 a nested 4-parameter solver with an output schema, this covers everything an agent needs: input shape, objective ordering, response fields, error contract, scale ceilings, and license gating. Nothing required to call it correctly is absent.

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 baseline would be 3; the description goes further with a worked input payload and an explanation of how fields interact — 'prefer'/'avoid' shift ids feed the third objective tier, 'weight' and 'skill' affect slot filling. It still leaves some fields (min_hours, max_shifts) to the schema, so not a full 5.

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?

Opens with a specific verb-plus-resource plus the constraint set it honours: 'Assign staff to shifts under availability, skills, hour caps and rest gaps.' That framing is unmistakably a shift-scheduling solver, which no sibling (bin packing, routing, knapsack, cutting stock) covers, so an agent can route correctly 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?

Gives concrete operating context — 'Use for weekly rotas of up to 60 staff and 150 shifts' — and an explicit exclusion: 'Not a determination of labour-law compliance: the rules are the ones you pass.' It also names the PREMIUM license gate. It stops short of routing to siblings such as validate_problem or explain_solution, which is the only missing piece.

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