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

Beyond the annotations, the description discloses the critical two-phase confirmation behavior, states that the first call has no side effects, explains that unknown fields are refused by name, and requires showing the summary to the person before confirming. It also states the required `content:write` permission. This is exactly the kind of behavioral context an agent needs for a non-idempotent mutating tool.

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 description is tightly structured and front-loaded: purpose, permission, call count, then the two-step flow. Every sentence carries useful information with no wasted wording.

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 mutating create tool with no output schema, the description covers the important operational behavior: validation-only first call, summary and confirm_token, human confirmation, and required permission. It leaves some gaps around the required title parameter, sibling tool selection, and what the second call ultimately returns.

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 schema already describes confirm_token in detail, and the description reinforces its role in the second call. However, the required `title` parameter has no schema description and the description does not explain what it means for a mix, so it only partially compensates for the 50% schema coverage.

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 and resource: "Add a mix." That clearly distinguishes creation from siblings like update_mix, delete_mix, and list_mixes by operation, though it does not explicitly name those alternatives.

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?

It gives clear procedural guidance for the two-call flow: the first call validates without changing anything, returns a summary and confirm_token, and the second call happens only after the person agrees. It does not discuss when to use this versus update_mix or other sibling tools, but the creation context is otherwise clear.

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