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

Annotations already declare the safety profile (readOnlyHint false, openWorldHint true, not idempotent). The description adds genuinely useful context beyond them: it is a POST streaming endpoint and costs 10 credits (Tier 1). It still says nothing about auth requirements, connection lifetime, or stream termination behavior.

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 core purpose is front-loaded in one line, followed by compact bracketed metadata for group, endpoint, and cost. No filler, though the abbreviation 'VOC' is never expanded for agents unfamiliar with the domain term.

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?

An output schema exists, so return values need not be described, and annotations cover safety. However, for a paid real-time stream with numerous closely related siblings, the description lacks the when-to-use and streaming-behavior context an agent needs to call it correctly.

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 description coverage is 100%, so both optional parameters (fields, precision) are fully documented in the schema itself. The description adds no parameter detail, so the baseline 3 applies when the schema does the heavy lifting.

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 names a specific resource and action: current Moon void-of-course status plus the next ingress. An agent can tell it produces VOC timing data, not raw positions or phases. It does not differentiate itself from the nearby astroway_stream_ingress or astroway_webhooks_void_of_course_start, which is the main gap.

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?

There is no statement of when to use this stream versus the sibling streams (ingress, transit_alerts) or the webhook variant void_of_course_start. The '[Group: Real-time Streaming]' tag hints at the mode but gives no selection criteria or prerequisites.

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