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

Annotations already indicate not read-only, not idempotent, not destructive. Description adds that each call mints a fresh invoice, requires authentication, has rate limit 10/hour, and describes renewal stacking. No contradictions.

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-loaded purpose, then returns, then follow-up instructions. Every sentence adds value. No redundancy.

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?

With output schema present, description covers return fields, idempotency, authentication, rate limit, renewal behavior, and status-checking alternative. Complete for a subscription tool.

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?

Only one parameter 'period' with schema description 'monthly or annual'. Description does not add extra meaning beyond the schema; 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?

Clearly states the tool mints a Lightning invoice to start or renew premium membership. Distinguishes from siblings by referencing colony_premium_status for checking invoice status.

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?

Explains when to use (start or renew) and what to do after (pay invoice, check status). Provides explicit follow-up steps via colony_premium_status or REST API. Lacks explicit when-not-to-use but is clear enough.

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