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

Annotations only declare readOnlyHint=false, so the description carries real weight here. It clearly discloses the confirm-gated preview/execute behavior and notes that prices are added afterwards, which are meaningful behavioral traits beyond the annotations. It does not cover permissions, duplicate handling, or what the preview contains, keeping it from a 5.

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 definition is tightly front-loaded in a few short clauses with no filler. Each clause carries a distinct fact (what it creates, unit semantics, period/interval meaning, pricing follow-up, confirm gate).

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 mutation with a confirm gate, a large nested input, and no output schema, the description covers the most critical behaviors (preview vs execute) but leaves many nested fields and return-preview details undocumented. It is adequate to start a call, but not complete for an agent reasoning about all pricing and session fields.

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 around 50% on a nested 13-field input object. The description adds meaning for interval (number of periods per billing cycle), which the schema does not explain, but it mostly repeats the schema's minor-units note and the MONTHLY/YEARLY enum for amount and period, and says nothing about currency, ownedByGym, sessionsPer, or the session-rule fields.

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 first sentence gives a specific verb and resource ("Create a coaching plan clients can buy"), which is enough to separate it from create_diet_plan and create_workout_plan. It never explicitly names those siblings, though, so differentiation is implied by the resource noun rather than stated.

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 description does give useful routing: per-currency pricing is a follow-up via update_plan_prices, and confirm: true is required to execute. It does not say when to create a plan versus use create_plan_share_link, list_my_plans, or the diet/workout plan creation tools, so usage is only partially guided.

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