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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds value by disclosing that it lists only the caller's subscriptions (scoping) and by enumerating the returned fields (id, type, params, created_at, last_fired_at, fire_count). No contradictions with 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 concise sentences: the first states the action and return value, the second gives usage guidance. No wasted words, and the most critical information (what it lists) is front-loaded.

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 simple list tool with no output schema and minimal parameters, the description is complete. It explains what is returned, that it is scoped to the caller, and why you would use it (review monitoring or find id to cancel). No significant gaps given the tool's simplicity.

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?

Schema coverage is 100% with the include_inactive parameter already having a clear description in the schema. The tool description does not repeat or add extra meaning to the parameter, so the baseline score of 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 uses a specific verb 'List' and identifies the exact resource: 'the caller's active subscriptions'. It also mentions the return fields, making the purpose unmistakable. While it doesn't explicitly name sibling alternatives, the resource and action clearly differentiate it from subscribe/unsubscribe and other tools.

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 states 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 a practical use case, though it does not mention when not to use it or alternatives.

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