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

Annotations already declare idempotentHint=true and destructiveHint=false; the description goes further by explaining *why* it is idempotent ('keywords already planned are skipped, so a retry never adds twice') and by describing the scheduling side effects (day occupancy, unwritten card relocation, next free publishing day). It stops short of permission/auth or rate-limit details, but the annotation bar is already met.

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 tight sentences, front-loaded with the action and cap, then the scheduling rules and idempotency. Slightly telegraphic phrasing ('With a day it takes that day') costs a little clarity but nothing is wasted.

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 need not be described, and the description covers the mutation's key side effects, limits and retry safety. It could still note whether the caller needs an existing planner or quota, but for a single-parameter tool this is close to complete.

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 real meaning: it explains the 50-item cap and, crucially, the semantic difference between supplying a 'day' versus omitting it—a distinction the schema's date pattern alone does not convey.

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 ('Add ... keywords to the Content Planner') and immediately clarifies the effect ('Each becomes a card'), which cleanly separates it from siblings like list_keywords, add_domain and add_question.

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?

The context for calling it is implied (you want keywords scheduled in the planner) and the day/no-day branching is explained, but the description never names an alternative or states when not to use it (e.g. versus list_keywords or move_planner_card).

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