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

Despite annotations (readOnlyHint=false, idempotentHint=true, destructiveHint=false) providing a basic safety profile, the description adds substantial behavioral context: OAuth account required, phone verification with a 10/day cap, webhook auto-disabled after 10 consecutive failing runs, and a signing secret returned only once. No contradiction with annotations is present.

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 information-dense and front-loaded with purpose, but it is a long single paragraph covering many details. Each clause earns its place, but the density and length prevent a perfect 5. The structure uses colons and examples effectively, making it scannable despite its length.

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 objects, 3 parameters, and no output schema, the description is remarkably complete. It covers return value (new subscription id), all supported types with examples, delivery channels, authentication prerequisites, verification steps, rate limits, and failure behavior. An agent has sufficient information to select and invoke this tool correctly without additional documentation.

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 schema already containing detailed descriptions for type, params, and delivery. The description adds meaningful usage context beyond the schema: concrete examples for each subscription type, the requirement for verified phone numbers, the always-on feed channel, and delivery constraint warnings. While not entirely novel, this supplemental meaning justifies a score above the baseline of 3.

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 a specific verb+resource: 'Create a proactive monitoring subscription to a live-data event stream.' It clearly distinguishes this from sibling tools like list_subscriptions, unsubscribe, and recent_alerts by focusing on creation and explicitly stating it returns the new subscription id. The supported types and delivery channels further reinforce the tool's unique purpose.

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 clear context for when to use the tool: to create a subscription that monitors live data, with explicit account requirements (Pipeworx OAuth, not anonymous/BYO) and a note that feed delivery is always on and can be pulled via recent_alerts. However, it does not explicitly state when not to use it or name alternative tools like list_subscriptions/unsubscribe for managing existing subscriptions, so it stops short of a full 5.

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