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

Discloses important behaviors beyond annotations: the current tier stays active until nextRenewalAt, the lower tier activates after that, no mid-cycle charge, and requires owner role with billing scope. This enriches the destructiveHint=true annotation with timing and auth details.

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?

Four concise sentences cover purpose, timing, key discovery, return value, and auth. Every sentence is informative and no content is redundant.

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 tool with no output schema, the description adequately explains the return value ({addonKey, targetAddonKey, project, effectiveAt}). It also covers scheduling behavior, prerequisites, and authorization, making it complete for an AI agent to invoke correctly.

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 input schema already provides complete descriptions for both parameters (100% coverage). The description adds no significant parameter-level detail beyond what the schema states, so baseline 3 is appropriate.

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: 'Schedule a tier downgrade for a non-stackable add-on (RPM tier).' This clearly distinguishes it from sibling tools like subscribe_addon or change_plan by specifying the action and scope.

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 provides clear context: scheduling happens at next renewal, with no mid-cycle charge, and points to list_addons for finding keys. It does not explicitly mention when not to use it or alternatives, but the context is sufficient.

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