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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds value beyond that by naming the four plan states that can be returned and by explicitly stating that mutations live in the app rather than in this API, preventing a misdirected write attempt.

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?

Two short sentences, zero filler, with the resource and its possible states front-loaded before the read-only caveat. Every clause earns its place.

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 zero-parameter read-only tool whose annotations already carry the safety profile, the description supplies the one thing still missing — the set of plan states the response can carry. No output schema is needed given that enumeration.

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?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. No param claims are made or needed.

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?

Names a specific resource (the trainer's own Trainer Connect plan) and enumerates the states it returns (active, trial, grace period, renewal), so an agent knows exactly what comes back. The 'own' scoping differentiates it from account-wide or student-facing plan tools, though no sibling (e.g. get_subscription, get_contract) is named as the contrast.

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?

States a boundary — 'changing the plan is in the app' — which tells the agent this tool is not the path for plan changes. However, it never says when to prefer this over adjacent reads like get_subscription or get_my_account, and no prerequisites or alternatives are given.

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