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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint-false, so the safety profile is covered. The description adds real behavioral value: delivery history ordering (newest first), per-page paging through deliveries_cursor, and inclusion of both payload and attempts. Minor gap: nothing about not-found behavior, acceptable for a fetch tool.

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 sentences with zero fluff: the first delivers verb+resource+output shape, the second delivers routing guidance. Every sentence earns its place and the core action 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?

With no output schema, the description carries the burden of stating the return shape and does so (payload + deliveries page). Combined with annotations (safety) and a well-described schema, an agent can select and invoke it correctly. Small remaining gaps: no error behavior and no boundary against aggregate siblings like event_stats/delivery_health, but these are minor for a single-fetch tool.

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 75% — id, org, and deliveries_cursor are already described; only deliveries_limit lacks prose, but its default/min/max carry meaning. The description contributes little param-level info beyond re-stating that deliveries_cursor is the paging handle, which the schema already conveys. Baseline 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?

States a specific verb (Fetches) + resource (one event by id) + what is returned (full payload and a page of delivery history, newest first). The positioning as a follow-up to search_events/get_user_timeline differentiates it from siblings without opening their schemas.

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?

Explicit workflow guidance: 'Use it after search_events or get_user_timeline when the payload or every delivery attempt is needed.' It names the tools that precede it and the condition that selects it, but does'nt explicitly state when-not to use it (e.g., when aggregates would suffice, such as event_stats).

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