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

The description discloses the return fields (id, type, params, created_at, last_fired_at, fire_count) and the scope ('caller's active subscriptions'). With annotations already indicating readOnly, idempotent, and non-destructive behavior, the description adds useful context about the response and scope without contradicting annotations.

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 sentences, front-loaded with the primary action and return value list. Every sentence earns its place: the first defines the operation and output, the second gives practical usage context. No filler or 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?

The description is complete for this simple tool: it states the return shape, clarifies the default scope, and provides usage guidance. The sibling tools include subscribe/unsubscribe, making the described use case meaningful. No output schema is needed since the description enumerates fields.

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 has 100% coverage for the single parameter, including its own description. The tool description adds minimal extra meaning beyond the schema, but it does imply that 'active' is the default and that include_inactive changes that, which is helpful context.

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 it lists the caller's active subscriptions, naming the resource and action. It also distinguishes itself by specifying the return fields and mentioning use cases relative to subscribe/unsubscribe ('before adding more', 'find an id to cancel').

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?

Explicit guidance is given: 'Use this to review what you're monitoring before adding more or to find an id to cancel.' This defines clear contexts for use, though it does not explicitly state when not to use it or mention alternatives beyond the implied subscribe/unsubscribe siblings.

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