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

Adds meaningful behavioral context beyond annotations: OAuth requirement, persistent feed always on, SMS delivery constraints (phone verification, 10/day cap), and the return of a subscription id. It does not contradict the annotations, though it omits webhook details and lists only three of the five supported types.

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 dense and front-loaded with the core purpose, then organizes types and delivery channels. It is longer than ideal but every sentence provides distinct useful information.

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 complex tool with nested delivery objects and five enum types, the description covers account requirements, return value, and main channel constraints. However, it omits webhook as a delivery channel and does not mention patent_grant or clinical_trial despite listing 'Supported types', leaving gaps that the schema partially fills.

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 description adds concrete JSON examples for type-specific params (e.g., items:["5.02"] = officer change, params:{topic:"fed"}, series_id:"UNRATE") and delivery channel constraints. The schema already provides detailed descriptions, but the extra examples meaningfully help an agent construct correct parameters.

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 opens with 'Create a proactive monitoring subscription to a live-data event stream' and states the new subscription id is returned. This clearly distinguishes it from siblings like list_subscriptions, unsubscribe, and recent_alerts by focusing on creation.

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 clearly identifies the tool's role—creating subscriptions—and gives prerequisites (OAuth account required; anonymous/BYO cannot persist). It does not explicitly name alternatives like list_subscriptions or unsubscribe, but it states when the tool is appropriate and provides delivery-channel context.

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