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

With annotations already declaring readOnlyHint=false and destructiveHint=false, the description adds substantial context beyond them: the operation is additive (other groups preserved), the group must pre-exist, it notifies no one, and it is undoable in TrueCoach, which explains why no confirmation is requested. It also names the auth requirement (Cotlet API key with app access).

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?

Front-loads the core action, then adds prerequisite and side-effect context. Every sentence carries information, though the colloquial phrasing ('does not ask for your OK') is slightly informal for a tool spec.

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 two-parameter mutation with no output schema and annotations covering the safety profile, the description supplies everything an agent needs: prerequisite, additive behavior, reversibility, notification behavior, and auth requirements.

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 100%, so the baseline is 3, but the description adds real meaning: the group_name must correspond to an existing group in Manage Groups, which is a constraint the schema does not express. client_id sourcing is already covered by the schema.

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 a client to a group) and clarifies the additive semantics ('keeps their other groups'). An agent can immediately tell this apart from other TrueCoach client tools like create_client or assign_program.

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?

Gives clear context and a prerequisite: 'The group must exist in Manage Groups.' It also notes the effect is reversible and silent. It stops short of naming alternatives or explicit when-not conditions, so it falls just below the top band.

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