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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds one genuinely useful behavioral fact beyond that - the account-owner-only authorization requirement - but says nothing about duplicate-name handling, limits on unit count, or what is returned.

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 sentences, front-loaded with the action, zero filler. The terse fragment "Only the account owner can." is slightly clipped but still earns its place by adding an authorization rule.

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?

A mutation tool with no output schema and fully undocumented parameters needs the description to explain inputs and side effects, and it does neither. It covers purpose and authorization but leaves an agent unable to know what a valid call looks like or what comes back.

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% for both parameters, so the description carries the full burden, yet it never mentions 'name' (required) or 'address' (optional) or any format constraints. The parameter meanings are only guessable from the property names themselves.

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 (adds) and resource (a unit/branch of the gym), with the parenthetical clarifying what a "unit" means. It is clearly the create counterpart to the sibling list_gym_units, though it never names that sibling explicitly.

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?

No indication of when to use this versus other setup tools, no prerequisites beyond the owner restriction, and no mention of related operations such as list_gym_units or how units relate to schedule slots. Usage is only inferable from the verb.

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