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

Annotations already declare this as readOnly, idempotent, and non-destructive. The description adds useful behavioral context by specifying the return fields (id, type, params, etc.) and clarifying that only active subscriptions are listed by default, complementing the annotation coverage.

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 two sentences, front-loaded with the primary purpose, and every sentence adds value: the first states what it does and what it returns, the second gives practical use cases. No wasted words.

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?

Given the tool's simplicity (one optional parameter, read-only), the description is fully complete: it lists the return fields, notes the default active filter, and provides usage guidance. With strong annotations and schema coverage, no further context is needed.

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 fully documents the single optional parameter `include_inactive` with a clear description, so the description doesn't need to add much. It does implicitly clarify the default behavior by saying 'active subscriptions,' which aligns with the schema's default false. Baseline 3 is appropriate given high 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 clearly states the tool's function: 'List the caller's active subscriptions.' It uses a specific verb and resource, and distinguishes itself from sibling tools like subscribe and unsubscribe by focusing on listing existing subscriptions.

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 explicitly explains when to use the tool: 'Use this to review what you're monitoring before adding more or to find an id to cancel.' This provides clear context and implies alternatives (subscribe to add, unsubscribe to cancel), making it easy for an agent to select the right tool.

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