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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the agent knows this is a mutating, non-idempotent operation. The description adds the admin prerequisite, which is a meaningful behavioral constraint beyond the annotations. However, it doesn't disclose what happens on failure (e.g., partial promotion if some members are invalid) or whether the operation is reversible.

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 with zero waste. The core action is front-loaded, and the prerequisite is stated in the second sentence. Every word 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 3-parameter tool with 100% schema coverage and an output schema present, the description is nearly complete. The admin prerequisite is the key contextual fact, and it's included. The only minor gap is not describing the output/return behavior, but the output schema likely covers that.

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 all three parameters are already documented in the schema. The description adds no additional parameter-level meaning beyond what the schema provides. Baseline 3 is appropriate since the schema does the heavy lifting.

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 description states a specific verb ('Promote') and resource ('group members to admin'), which clearly distinguishes it from sibling tools like wa_demote_participants and wa_add_participants. It doesn't explicitly name the sibling it contrasts with, but the action is unambiguous.

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 gives a clear prerequisite ('The account must be a group admin'), which is useful context for when to use the tool. However, it doesn't explicitly state when not to use it or mention alternatives like wa_demote_participants for the reverse operation. The prerequisite implies usage context but doesn't fully guide selection among siblings.

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