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

Annotations already declare readOnly=false, idempotent=true, destructive=false, openWorld=false, so safety is covered. The description adds real behavioral context beyond them: collision behavior (the two cards swap), refusal semantics for occupied days, and the fact that the operation costs nothing ('Free'). Return format is not described, but an output schema exists.

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?

Four short sentences, front-loaded with the action, then collision, then refusal, then cost. Efficient, though the trailing one-word 'Free.' is telegraphic and slightly unclear in isolation.

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 an output schema present, return values needn't be explained, and the description covers the mutation's preconditions, collision resolution, and cost. What remains thin is parameter-level meaning (which day format, which card_id), the only real 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 description coverage is 0% and the description never explains card_id or day. It implies day is a publishing date, but the card_id semantics and what 'not written yet' means for the identifier are left entirely to the schema's patterns/formats, which do not compensate for the coverage gap.

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 (Move) and resource (planner card) plus the scope constraint that only unwritten cards can be moved. An agent can distinguish this from sibling tools like get_planner or replace_article without opening the 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 preconditions: the card must not be written yet, and the target day must not be held by an article in progress or published. It doesn't name alternative tools, but no sibling performs this operation, so the conditions are the useful guidance.

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