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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so the description doesn't need to cover safety. It adds value by disclosing the return fields (id, type, params, created_at, last_fired_at, fire_count) and the default scope of 'active' subscriptions, which is useful behavioral context beyond the 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?

The description is two sentences, front-loaded with the main action and return fields, followed by concise usage guidance. Every word earns its place, with no redundancy or fluff.

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 read-only list tool with one optional parameter and no output schema, the description is complete. It provides the return format, scope (caller's active subscriptions), and usage scenarios. The annotations cover safety, and the schema covers the parameter, leaving no significant gaps.

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 already documents the only parameter, include_inactive, with a clear description and default. The description's use of 'active' adds some context about default behavior, but it aligns with the schema's default false. No additional meaning is provided beyond the schema, so the baseline 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 clearly states the action ('List the caller's active subscriptions') with a specific verb and resource. It also lists the return fields, which distinguishes it from sibling tools like subscribe and unsubscribe. The use cases ('review what you're monitoring before adding more or to find an id to cancel') further differentiate it.

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 provides explicit scenarios for when to use the tool: to review active subscriptions before adding more, and to find an id to cancel. This gives clear usage context. However, it doesn't explicitly mention alternatives like subscribe/unsubscribe or state when not to use it, though the context is implied.

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