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

Annotations already mark this read-only, idempotent, and non-destructive, and the description adds genuinely new operational context: the 100-event window, immutability of events, free-of-charge, the required webhooks scope, and out-of-order delivery handling via dedup on event ID. That is substantive disclosure beyond the structured fields.

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?

Three tight sentences, front-loaded with what is returned and how many, then cost/scope, then operational guidance and the sibling alternative. No filler or restatement of the tool name.

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?

With no output schema, the description carries the burden and does so: it enumerates return fields, caps the result size, states the auth scope and cost, and warns about out-of-order delivery. Nothing needed to call this correctly is missing.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The mention of stable id/type/data/createdAt describes the payload fields, not inputs, so it does not add parameter meaning still owed.

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?

States a specific verb ('Read') and resource ('this organization's ... lifecycle events') with explicit scope ('last 100') and returned fields (id, type, data, createdAt). An agent can distinguish it from replay_event and get_webhook_deliveries without opening a schema.

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?

Explicitly routes to the alternative: 'Use replay_event for a known event and active receiver,' and states the scope prerequisite ('Requires webhooks scope'). It lacks an explicit when-not-to-use-this condition, but the alternative routing and scoping requirement are clear.

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